As is clear on the O/P, this is a discussion on the "mp war" and whether one believes "more is better" or if the drawbacks are more than the gain... Most posters seem to agree that with too high mp count there are more problems created and no real benefit added.
I guess the next step in a discussion is for posters to suggest (and back up with evidence) what the optimum should be... meaning the point where more resolution is pointless, quality benefits from other than resolution factors and also, usability of an MFDB expands... On the later, many seem to agree (especially those that use technical cameras) that if a back doesn't perform well on a tech camera it is a serious drawback for ones photography.
Obviously, it is natural for one to link the subject under discussion with the latest Sony MF sensor since it sets a new record on mp count among MFDBs and is only second to Canon's 5ds among "large sensors" (meaning FF size and larger) for smaller pixel size.
My personal opinion, is that it would be best if the same sensor was of 6μm pixels, would have "only" 60mp of resolution for the same size and the pixels where more "friendly" when used with cameras with movements. I would even prefer it more if it was of a bit lesser size (the traditional 49x37 comes to mind) as with 24 & 28mm lenses available, there is no problem for one to have an UWA lens but all lenses of a platform would benefit too for edge IQ at the same time, as well as having extra image circle tolerances that would allow more movements on a tech camera. The resulting 50mp or resolution (for 6μm of pixel size at 49x37mm sensor size) I wouldn't mind at all...