The match you're complaining about Dante was a fairly close match against the level 29. If he hadn't of killed you with his last turn you would have managed to kill him on the next, so it still was a fairly close match. That's the only lose I could find where the opponent was 6 levels higher than you. The rest have been 3 or less, so it's not a HUGE problem
I have to agree with MrOneTwo slightly though. The exclusivity of weapons means those who are dominating lower levels will continue to dominate lower levels for the rest of this games career (unless people make multiple accounts). By the time you reach level 15-20, you probably don't have a full concept of how the game works. To then be denied the stronger weapons of the game as well as being put behind on fusion makes it pretty much impossible for these guys.
Fusion isn't a huge factor in a fight. Sure you're going to find it a bit easier if your mech is highly fused. However your match will still be a close match with a mech similar to yours that isn't fused. A lot closer than a mech that can't get the weapons the top players own
Back to the original problem of players fighting at too high of a level, I don't see this as a problem. If it's happening to all top players then all top players are at a disadvantage, aside from those at level 30. This isn't wrong as it encourages top players to fight at their own level and stops the lower levels players from dominating their level.