Is it just me or tenacity does nothing

There are quite a few videos out there that display the effectiveness of tenacity, however after a certain point it isn't worth it anymore because its bonuses are multiplicative instead of additive.

No , it's pretty strong it just doesn't work against knock ups

I believe more because of the dmg creep that 1.5s still feels like 30 years.

Kinda, but it is really satisfying to turn a Morgana root from 3 seconds to 1 second when I play Garen. The power of tenacity is so slight in a lot of cases that most people miss it in the heat of the fight. To me it is very helpful because I am a juggernaut main.

it's not that tenacity is bad it's just that you'll still die before you can move again

Nah it’s pretty effective. Especially when you build enough tenacity on someone like Darius or Illaoi. People underestimate how long you’ll be caught and you’re already in their face before they can react. Do like mercs, Steraks, unflinching (rune), legend: tenacity and elixir of iron and they can’t hold you down.