Yeah I'm actually shocked that Kizaru destroyed Snakeman like that.
Kaido's REALLY fast, and he had mild issues dealing with Snakeman at first, due to the fact it doesn't really make sense in regards to what Luffy's Fruit was supposed to be.
Kaido's a different beast since he actually wanted to be defeated and die, while Kizaru is not suicidal and is just straight up trying to execute people, but, still, pretty shocking.
Snakeman is not a weak form, and Katakuri was (despite what some people think) not weak.
Gear 4 is now strong enough to clear most Commander level enemies, but Luffy clearly needs Gear 5 to actually beat top tiers in 1v1s. Which is what makes it difficult to scale Luffy, you have to factor that his strongest techniques and forms leave him vulnerable, while other top tiers don't really have those limitations in a lot of cases.
Pica Pica no Mi Awakening next, let's get it.