Let me clarify what I meant (bad syntax on my part): It would be easier for a new player to get the building set if it started out in an event, rather than in the MA for crafting. New players would struggle to come up with the CCs needed to craft the building (unless it was ridiculously cheap to craft).
From my perspective, I don’t care if people end up with multiples of this set. If this is how they get their CCs, mana, seeds, supplies and coins, how does that hurt me? It’s not like the moonstone set which has created an imbalance in trade. It will benefit one badge in the FA. Personally, I can live with that if it helps newer players gain combining catalysts to craft items sooner. It beats them struggling to get CCs when they don’t have the relics to craft them, struggle with spire (or are in a FS that doesn’t do the spire, or a FS of all new players who can’t do the spire).
And let‘s be honest, is there really any way to make anything that players can’t spend money to get more of? And what if they do? Who does it hurt? If players stop spending money, then the developers stop the game.
Other than trader set, there hasn't been a multi-part bonus set from an event in quite some time. It's too easy to have someone get partway through the event, and miss out on one of the buildings. Missing a link bonus on the buildings you do have, is a lot bigger impact than missing a single evolution on an evolving building. Also, events typically aren't made to be easy for new players (i.e. at least based on playing Ch 2-5 cities).
Allowing multiple sets is a terrible idea, and has caused huge problems in the past (i.e. Spire set, brown bears, etc.). If you can get several multiples of 21 CCs a week from effortlessly collecting once a day, you've removed a huge portion of the incentive to actually play the Spire. For goods, you'll wind up with people with no regular T1/T2 manufactories.
I have ~10+ spire sets, and get way more CCs than I'd ever need. I craft stuff I'll never use, just to get a chance of getting 500 diamonds from the bonus chest. I'm sure that's something Inno would look at, if they're adding a large new source of CCs.
Since it doesn't seem like Inno is planning on changing the Spire set, personally I think they should strongly nerf it in upcoming chapters to get people to start deleting them, vs add in new sets to balance out.