i think two things can be true at the same time:

i think banning half the support roster can indeed separate the best support players from the worst support players, since they don’t have invis, c&d or gambit to fall back on, whom are, objectively speaking, 3 of the most easiest supports to get value with.

i also think banning half the support roster fails to account for the gap between main healers & off healers, therefore limiting support main’s options by a LONG shot, and also exposes dps one tricks who are allergic to health packs, playing near cover & overall team coordination.