Im sorry but yes its dumb to compare king to katakuri when it comes to reaction time and same with zoro to luffy
Luffy knew before any of the supernova hakai was happening. Being the first to call it out and first one on the offense after. Their was no point of luffy risking his body tryna block it when they wouldn't be able to win without him
I am fairly confident that you have no reasons to explain why it's dumb besides you not wanting it to be true. Katakuri and Luffy may be better than King and Zoro or maybe they're not. We don't know the answer, so to sit here and act like there is no other possibility is irrational. Also, I think you're confusing precog with better reactions. Luffy is able to see everything before non-FS users; this applies to those faster than him too. The difference happens only when reactions are taking place.
You can only react to an attack in the present—most people overlook this. If you're reacting to something in the present physically, then there is always room for others to react accordingly and counter you even if they don't have FS. Luffy saw Hakai coming but he couldn't react on time and risked his losing his life without doing anything while Zoro reacted quickly and saved everyone.
Luffy knew before zoro even mentioned anything about apoo attacking again. He just didn't know how to block it
They sensed it at about the same time almost; that's the whole point of the interaction. Obviously, Luffy learns it before Zoro because he's got FS. The point here is Zoro was almost as quick as Luffy to notice even without FS.
No not when it comes to reaction speed
Having fast attack speed =/= fast reaction speed
Someone with fs is still going to react faster than those without
Reaction speed and attack speed are different but you use your attack speed to react to attacks sometimes, so there's an overlap here and there. So the faster you strike, the faster you could react. They complement one another. People with FS need to be physically fast enough to be able to react faster than their opponents. This doesn't always work because people can be too fast to react even with FS sometimes. This speed doesn't necessarily have to be movement speed.
Marco is nowhere near admiral level
Marco isn't comparable to kizaru just because they had small clashes
Lol, you don't have to be admiral level to operate at those speeds. You could be far weaker than someone and still have some stats better than them. Marco canonically kept up with Kizaru, period. So if Luffy struggles against the same or if Kizaru's able to deal with Luffy without struggling, then Marco could do the same as far as speed goes.