Really, its nonsense. Certain champs can carry harder, we know that. And certain positions tend to carry harder as well.
So if you aren't playing the right champions, and the right positions, despite what you might want to play, you don't have as much control over the ability to win a match as others do.
This seems wrong. I think most champions should have a mechanism to at some point the match to carry.
Furthermore, the idea that some champs are harder to learn and therefor they are more powerful, is absolute trash.
So if 2 players pay the game for months, one picks an easy to learn champion, the other a harder to learn and harder to play but stronger, in the end , the first player is going to be way behind the power curve.
Saying that some champions are harder to learn or play is just a way to leave certain champions in too strong of states.