Wikipedia informs me that "many masses, especially later ones, were never intended to be performed during the celebration of an actual mass." But what about Bach's Mass in B Minor? Did he intend it as a performance piece, or did he also wish for it to be used as the Sunday Mass? Was it ever used as such? If so, was there full participation by the congregation, or did they mostly just listen?
If evidence is lacking with regard to Bach's Mass in B Minor, then what about similarly complex Masses from around the same time period?
Bach's B Minor mass is a particularly strange case because the mass is a Catholic genre, but JS Bach was Lutheran. Why would JS Bach compose a monumental piece for a denomination whose fundamental tenants he didn't even believe in, and that was at odds with the church(es) where he was actually music director?
A typical Lutheran Sunday service, just for comparison, would not have had a mass. For those, JS Bach composed several hundred cantatas, at one point composing one nearly every week (!!) for performance that Sunday, and then just repeating those once he'd written them. These have a mix of genres in them, with a lot of music for vocal soloists, though it's based on a chorale tune that the congregation would have been familiar with (see my previous answer here).
The common wisdom I've encountered when reading about JS Bach's B Minor Bass is essentially that it wasn't necessarily even intended to be performed at all, but rather that it was assembled for the sake of being a compendium. I'll go by this article by Christian Wolff (probably one of the foremost JS Bach scholars these days) and highlight a few crucial points. Firstly, the mass wasn't composed from scratch, as one might imagine now: much of it is repurposed from other pieces (and indeed, a lot is in D major!), some of which (such as the Kyrie) had been performed in Lutheran churches on special occasions. But when he added more movements, those were irrelevant to any service he'd likely direct.
But because of the changes to the text for earlier Protestant movements, Wolff concludes, from the piece being liturgically unusable, that it was written "in particularly by the 'connoisseurs of this kind of work'" (60).
What's the point, then? Essentially, just putting a lot of smaller movements together, regardless of their sources, to form a compendium. Some parts of it might have been for a sort of job interview at Dresden, which was more Catholic, but that was an earlier, smaller part of the mass (see Wolff page 56). But he continued working on what we now know as the B minor mass almost to the end of his life; Wolff hints that he was leaving it for posterity.
So, there is certainly evidence around the B Minor mass, that it was not intended for liturgy, but that many of the individual movements were.