What June has been saying is actually pretty much completely true. I have seen first hand that people don't even attempt to adjust how they play against pyros (or don't know how to) and instead prefer to complain about it. Pyro is annoying, unfun to play against, has a completely broken skill to reward ratio, and is one of the most conceptually broken concepts executed in the game. Pyro isn't overpowered, doesn't centralize the game, and doesn't show any signs of being absurdly powerful except at low levels. Saying that the only counter to a pyro is another pyro or that there is no counter is fucking retarded. Literally equip a shotgun on soldiers and treat corners cautiously and you are 90% of the way there without even venturing remotely into the land of gimmicks.
The most basic change that could be made to it right now is making it possible to see through flames holy shit that is fucking aids. Past that, people have always said to make the class reward aim and movement. Jungle inferno buffed pyro, but somehow managed to make it reward aim and movement EVEN LESS than before, which is rather depressing. In terms of getting valve to change pyro to have an actual skill-reward system, its most important to make sure that the community at large knows why making pyro reward good mechanics is important so that valve actually has the consensus and pressure to make changes rather than seeing the topic as a landmine they don't want to approach again.