I understand that, I mentioned that in my post.
However we have to use common sense here. Generally, the weaker guys get beaten before the ultimate final showdown. That's normally how it works. Urougue beat Snack and then Smoothie mentioned how Cracker was sent in after that. You don't send in someone weaker than the guy who got defeated. And then, Katakuri was the final man. We can compare feats, and Katakuri has a higher bounty and more impressive feats. Like I said, in Shonen the weaker guy gets defeated before the ultimate showdown against the strongest man. Luffy prevailed against both of them.
I understand that whole tier thing, but you can't place Urogue above Luffy because he beat Snack when Luffy prevailed against 2 commanders who were placed on a higher pedestal than Snack. Snack was portrayed to be below Cracker, and Luffy beat someone who was stronger than Cracker so him having help against him doesn't negate the fact that he beat someone seemingly stronger than him.