There is no "left brain/right brain" differentiation. That's a myth.
But you seem to be having fun so I'll leave you to it.
Well, you may be right that the left brain/right brain distinction is "old school" and, when used as if they were completely separate is a "myth," but when you do a corpous callostomy (cutting the corpus callosum) you can measure each sides electro-chemical response to certain kinds of stimuli. And when you do, there is a difference in the responses you get from the patient. In experiments done over one hundred years ago and repeated many, many times, you find the left hemisphere of the brain (because it's, technically, not a separate brain) responds to linear simuli overwhelmingly more than the right, and the right brain hemisphere to stagnant imagery more than the left. Patients response to each test would indicate that each side is processing the stimuli differently because the responses of the patients to the stimuli is different when each side is triggered. Now, in the long run, because the two must work together, the size and density of the corpus callusom allows the two to resolve the difference in response (i.e. the interpretation) of the stimuli. If you follow the line of reasoning and experiment Roman Jakobson started over one-hundred years ago you can easily discover the differences have been medically substantiated many, many times.
Now, to your larger point, perhaps. Yes, there was a crazy over-exaggeration of the differentiation of the two sides of the brain. Yes, people started acting as if it were two separate brains and made all sorts of claims based upon that mythic understanding. But, sadly, that's what often happens when the media get a hold of an idea -- they tend to overstate it to make it more exciting and thus to sell more media. But let's not ignore the science and go the opposite way to overstate the case against the idea. That too, is not warranted. I suppose, in the end, it depends on how much of a difference in response you find between the two hemispheres that determines if you take seriously the Left/Right brain distinction.
And finally, when discussing something, it does little good to simply make a counter-claim and expect that, one supposes, because you made the claim the reader should automatically assume you are right. That you simply say the distinction is a myth and then add "But you seem to be having fun so I'll leave you to it" sounds a bit, to me, dismissive. Now think about that. Not only do you make a counter-claim without giving any evidence as to why the reader should believe your claim over that of the other side, you then dismiss the other side as if -- what? -- that we are to just take it you know best? Certainly you have a right to your opinion. But if you want to be helpful rather than just expressing your emotional state (which is the theme of this thread), wouldn't it be better to add at least some link to where we can see some of the reasons/evidence upon which you base your claims?
Just in case somebody is still sticking by what they learned in High School Biology, let's reference an interesting article that was published in 2013.
Left Brain / Right Brain
First, I didn't learn it in High School. LOL!
From the abstract: "Lateralization of brain connections appears to be a local rather than global property of brain networks, and our data are not consistent with a whole-brain phenotype of greater “left-brained” or greater “right-brained” network strength across individuals."
The experimenters were not asking the question: "is there a difference between the two sides," but instead "can one side be dominant over the other?" The fundamental question, therefore, is not addressed by the overall experiment design.
Sadly, though, the whole thing may be a red herring. Nobody, to my knowledge, has claimed a full left or full right hemisphere involvement in any stimuli presented (i.e. the "two independent brains, idea). Everything I've read indicates the experiments focus not on where the brain response occurs so much as on which side is dominant in that response. Thus, it may be that one area of the left brain responds to symbolic presentations more than the rest of that side, and that is in the data, but it gets reduced to "the left side," rather than being more specific (perhaps because the experiment design does not call for it to be more specific even if it was). In any case there are two problems with the whole "right brain/left brain" controversy. And both are rhetoriczl
First, those opposing writers are often in a position where they want to publish. That something that undermines a distinction assumed or at least used in discussions, is more likely to be published than something which simply reinforces the distinction, makes it more likely researchers will put more effort into making the case for their work. They may be right, but once they get to the idea that they are challenging some assumption, they can easily miss things. And those who read their report may be in the same boat, wanting to disconfirm something "everybody" is certain is right.
In this particular case, the researchers set up their experiment to answer the question: "Is right or left brain dominance a thing?" They weren't asking the question: "Is there a difference between the two hemispheres?" Since they were asking about dominance they attempted to create an experimental design able to determine the answer. The experimental design is insufficient to determine if there is a difference between the two hemispheres of the brain because it wasn't designed to do so. That they imply that the distinction between the two sides may be a myth, is, sadly, what people do when they want to challenge the "old school" views. Almost ever document I've ever read tends to exaggerate...even what I'm currently writing! LOL!
Second, the whole "left brain/right brain" idea is an exaggeration of the research. But that it is does not mean the two are identical in function or response. The popular media of science writers, since the 1960's has churned out article after article of exaggerated claims of science. All experiments have a level of confidence, and while it may be 99%, it's recognized that the conclusions could be wrong. But the media often presents what "scientists have learned" as certain, and then, simplifies it for the lay audience (or sometimes for less informed collegues). The reports of the differences in the left/right hemispheres of the brain done in 1957-1959 were used to popularize the "two brain" hypothesis (which no competitent scientist actually subscribed to that I know of) in countless articles (and text books) were summarizes of the experiments done, and were greatly simplified and exaggerated.
Third, What the usual verbiage used, that "the chief processing of the stimuli occurs on the left side of the brain" is easily, and often, short hand for an observation of responses on the left side of the brain. It is not saying "all the left side of the brain responded." That those reading often made the short hand into what it was not, is to be expected and led to the the 1960's "left brain/right brain myth." After all, it is not a difficult thing to say, "potatoes come from Idaho" when they are grown primarily in southern Idaho. The first includes the last but is less specific. So the "left brain/right brain" distinction is an less specific, short hand, description of something which occurs in each side, though, perhaps, very localized to sub or independent small networks in those sides.
AJ