In reality the meta does not matter for the part of M+ that is progression; everyone can do +15s in time, you don't need the extra tank damage or the insane burst AoE so you can do larger pulls. But there should still be some effort to tune for higher keys (especially given the focus they give to Dungeons as esports). But ofc player perception is always problematic and meta specs effectively get a bonus to their rating as far as some people are concerned.
Still think they could make their lives more easy if there was a separate gear progression for Dungeons (so you'd have PvP, Raids and maybe even a World progression track).