Yeah i too see this as an game breaking issue.
It shouldn't be that only realistic way to win is to play at the max level, which btw i would say is the most boring level in the game. Only player i have ever seen to hit the top without level 30 build is MrOneTwo, and it probably required a huge amount of work from him to manage that. There is basically those 2 lvl 30 builds that just rule all, you never see any other build break the top 3 these days. I say reduce the matchmaking difference to max 4-5 levels, and everybody will be happy.