the "but it benefits the tier defensively" argument never held water—if something is broken, it doesn't matter whether it brings value to the tier, it should be banned. whatever consequences that ban brings, it should happen regardless. remember dlc1 gliscor? it buffed a ton of defensive playstyles that otherwise were just straight-up not good in dlc1. but we had to get rid of the mon anyway because it was broken, and that was ultimately the right decision (stop crying about zap-king-lu balance, it was fine). remember archaludon? outside of its one broken move, it had a fantastic defensive profile and could have easily been one of the biggest defensive powerhouses of the generation. but the electro shot sets made it broken, so it had to go. if we want to keep mons that are broken on the whole but benefit the tier in some specific way, the only feasible way to do that would be to isolate and remove the broken part while keeping the useful part, which would require either a substantial policy change (for signature moves like electro shot or come-on-they're-basically-signature-no-one-else-uses-this moves like rage fist) or complex bans (for something like volc where there's no easy way to isolate the contentious part without massive collateral damage). the latter is anathema to tiering philosophy, and the former is something that i personally would like to see happen but the higher-ups are vehemently against
tl;dr no one cares if something broken has defensive benefits, get it away
tl;dr no one cares if something broken has defensive benefits, get it away