I disagree. It’s fine, healthy even, for a competitive game mode to properly reward its most achieving participants.
WoW arena is one of the most difficult competitive PvP games out there. You need to understand and master hundreds of spells, mechanics, interactions, and to master positioning, all while tracking the CDs of 6 different players all at once.
As far as complexity is concerned, I would argue that WoW is on par with StarCraft II.
However, I do agree that Blizzard are making a mistake by only rewarding high level players.
I actually made a very high quality thread about this. Feel free to like it: