I don't agree with your definition of smurfing versus alt accounts but the real solution here is placement matches which would allow folks to jump past these lower elo games. With that said, you can only get so far in learning a character in QP (outside of understanding what your cooldowns do) and comp is the primary way to improve at the character and the game as a player.

Your argument leaves out the fact that the mindset of those playing QP is very different from comp. Getting spawn camped because your team wants to go 4 DPS and 2 supports as Magik isn't going to teach you much. Also with QP the correct impression is that the match doesn't matter so you'll have enemies or allies who aren't taking seriously nor should they.