Not banning an ability just because it's not bugged isn't really a valid reason, like the rule clearly states any move that causes a shift in accuracy or evasion, abilities shouldn't be treated different than moves.
I honestly can't find comprehend a reasonable reason to not ban those abilities outside of "customer satisfaction" for the players that already invested time into pokemon with those abilities but the whole purpose of banning those abilities in any competitive play was the evasion clause