As someone who regularly reviews cameras and lenses for different publications, you make an excellent point. So far I haven't encountered the problems you cite with any of the DSLRs I've reviewed. Several years ago I tried to sell the CEO of Nikon on the idea of incorporating the Arca-Swiss dovetail QR plate into their camera design but all I got was a quizzical look.
Thanks. None of my old Nikon SLRs or DSLR hade any problems. It seems to be design flaw for some mirrorless where the stability is sacrificed for compactness. For some no loss, for others as me that consider the new mirrorless as practical digital backs an irritation.
Btw, had a Pana GH-2, the base of this was no problem for tripod work.