Do you see Blizzard devs winning all Warcraft 3 tournaments?
You see EA developers scooping up all trophies for Need For Speed or Battlefield?
Do you see Valve people pwning all else in Counterstrike matches?

Creating a game involves programming, design, etc... Unless one of those things suddenly became essential for you to pwn in DotA, I highly doubt any developer on the DotA team is automatically uber in the game.

The only devs I know that are actually pretty damned good at the game they make is Bungie... They have events where they play against regular joes... and they just eat their asses.

If a developer is somehow unbeatable at the game they make, chances are, they're probably exploiting something most ppl don't know about (AKA, legal cheating, etc. ).