No I'm not saying that only top five are qualified to give advice. I'm saying that YOU are not qualified to give advice.
Lmao so if I tell you 2+2=4 and someone else tells you 2+2=4 who's right?
That's a degenerative mentality that is going to slow your progress, you should filter the advice you take yes but you also should consider conceding on topics you are not versed in. AirFair was 100% right. Think about what is being said not who is saying it.
By your own logic you may not be qualified to refute anyone's advice.
A lot of what people will tell you is often a second hand version of what some top player said or general knowledge. If you think they're wrong, which is okay, you should ask them why or to explain further. So you don't cut yourself off to information that will make you better.
What part about learning the threatening ranges you have while in X state (stand, air, dash, run etc.) & the threats your opponent presents in their state seems wrong and bad to you?
That's basically how you play melee (once you grasp that approaching is typically bad, that's step 1).
You start getting better once you reverse construct your game and gain ituition and experience as you try to play without being aggressive or easing up. Try running away from your opponent flat out or just avoiding them and see how the game "feels" and think about what you could do to them. Baby steps. Then try to build an offense around that. That is simply put but it'll make a lot of ideas fall into place and basically AirFair said the same thing with different words and ideas but it's all the same.
Don't be afraid of knowledge or using critical thinking, melee is simple in concept but hard to play.