Being arch of a team of about 18 folks, we're always recruiting, because in real life there's going to be a little churn - last January we were smaller and took in all of a smaller fellowship, one of whom, bounced because it was "too busy" (at the start of the January FA), and a couple of whom faded from playing over the next few months, but the core 3 of whom are good players - who have been playing for years - without having seen the Pits of an FA before, or that tenth chest in Tourney.
It's not hard to recruit solo players - one finds them on the World Map, just up or down from oneself in the stats list, here in the forums, and some few on Elvenstats (though the latter offers way too many dead accounts to be really effective, alas). But as to inviting smaller fellowships: we've just invited a group of three to *all* join, as we did with that FS of six in January. We don't care if they're small, and the comradeship of folks who've alreay been playing together just adds good things to the connection in the larger groups. Seeing someone light up over what it means to get that tenth chest in tourney, who has been playing for years before seeing it at all, is awesome.
I guess what I'm musing is, why would folks poach when they can throw the doors wide open to welcome all of a smaller group?