Not controversial, but non-responsive.
Let's say, for the sake of argument, that one player being too good at combat is messing up your campaign.
Why is it messing up your campaign?
Because the other players suck at combat?
Because the others players don't want to engage in combat?
Because the DM keeps trying to challenge the one player who is "too good" at combat and winds up slaughtering the other PCs?
Because the player who is "too good" at combat makes an effort to try and teach the other players tactics and those other players are getting bent out of shape about it?
Meanwhile, let's examine his "solution": combat is now less relevant to the campaign.
What replaces it?
What if the players suck at what replaces it?
What if the players suck even more at what replaces it!
What if the player who was "too good" at combat is the only player who doesn't suck at what replaces it?
And then let's consider the game design principle here.
I saw something similar in regards to BECM/Rules Compendium D&D. One of the designers got rather snippy about higher (Companion and Master) level play, pointing out that PCs weren't supposed to be doing the same sort of dungeon crawling and such that they did during lower (Basic and Expert) level play. You were instead supposed to be doing political and rulership stuff at Companion level, and plotting your pseudo-apotheosis when you hit Master level.
Of course, the published adventures really didn't support this very much, being way more combat oriented with the non-combat stuff slipped in here and there. So apparently, the designers couldn't actually write publishable adventures according to their standards.
More, why exactly would you design a game that is played one way at the beginning, another way in the middle, and a different way at the end? Triathlons, BASEketball, and Calvinball excepted, that's like playing football for the first quarter, baseball for the middle innings, and ending up with basketball at the end.
But then it is the fault of the players and DM for not getting it right?
Which sounds a lot like their rhetoric during the roll-out for 4E, blaming players of 3.5 for not knowing the right way to have "fun".