>>280334558>>280334940I'd say that's more the result of OPM pointing at the powerlevel barriers you often find in shonen and such and taking that to its logical conclusions where 'only the S-class matters' is the unspoken rule, even in universe.
Most A-class we've seen aren't weak or anything, compared to the lower classes, but as that one page states: S-class is just insane.
Promoting into incompetency does still seem to be a problem in the MA, though, with Death Gatling's hit squad being largely composed of B-listers, that I recall. Preemptively: It was from the manga, yes, but that was before that went off the deep end, and clearly had something to say, unlike most of the later bollocks.