The point is that you can completely cheese the skill 'requirement' because of a broken / unbalanced mechanic.
Let's take Super Smash Brother Melee.
If two people of equal skill competes against each other, one is Falco the other is let's say Game and Watch. Falco is going to win with all the abuse and uses that he has. Hes essentially higher tier. Taking a high tier character and going against a low tier, the high tier is going to win, and even if the low tier is even more skilled, hes going to lose because of the character differences.
Falco can just reflector / down spike and repeat that (assuming you're good enough) and do that before just finishing the person off, or Fox can just reflector / wave dash you around the arena for giggles. Take Mewtwo or Game and Watch or Bowser or whatever low tier you want to shove in there, they can't do these things, they don't have mechanics that are just utterly broken.