Thus my question is this: Has there been a shift on how people think about BIAB from a practice tool or using it to work out songs to an actual source of quality tracks that can be used in a final mixes?
I can only speak for myself of course, but I use RealTracks for the final production.
I used to produce and mix local bands, and compared to their almost unsalvageable trainwrecks of recordings , RealTracks are REALLY good.
Good as in "professional musicians recorded by a professional sound engineer".
Some of them need a little love to shine, but in general they are very usable.
And if I can't find anything suitable for the song at hand, I can still record my own stuff.