I have a lot to say about this video, but Jello's section about meaningless characters is really what stood out to me, even as someone who personally has admittedly really shit takes on One Piece myself.
Firstly, a lot of it's just wrong. For example, you can't cut Trebol out of the story because if he didn't kick Usopp's ass, Dressrosa probably would've gone very different and a lot of plotlines that are ordained for the Final Saga wouldn't be able to happen.
Slime literally says Kidd, Killer and Basil Hawkins are insignificant characters whose removals wouldn't change the story, just to give an idea of the level we're at with this.
Secondly, what's even the point? Most of these are just minor characters which are designed to keep the story flowing, exist for some logical purpose, and/or barely even appear after the arc they're shown in. Removing them would detract from the story, especially in Water 7, Skypiea, Impel Down and Dressrosa.
You could say the same thing about some of these characters as you could about getting rid of Commander Cody in Star Wars Legends and giving his plot elements to other characters, like Rex. But what's the point of removing a character whose presence does add at least substance to the story?
Lastly, even on a small and unsubtle scale, the series is littered with stuff like
this to illustrate the dynamics between the Strawhats. It's as if Jello's so completely illiterate that the existence of side characters clouds him from seeing anything but goon material.