snipperino
Maybe in lower level 6s, a la UGC, pyro would work okay. There's a few posts and threads on SPUF and the tf2 reddit (
here have one that talks about a ugc plat team that ran a full time Pyro) as to why it's not the best idea against better players.
Most posts I've seen cite a lack of mobility as the problem. Sure that doesn't sound too bad, but it means your team will be a player down at mid until you arrive, and you won't be able to take high ground or rotate positions with your team nearly as well as a Scout or Soldier could.
I also wouldn't say that pyro absolutely counters the other classes; a Scout can flank him, reflects on jumping Soldiers aren't always reliable, and Demomen will simply airburst their stickybombs in your face.
of course I don't have 6s experience myself, but since I'm kind of a pyro main at this point I've looked into this a bit on my own.
Even if the reserve shooter was the only problem, it's just not a fun weapon to fight against. It punishes scouts and soldiers for jumping, and Pyro doesn't even have to try to get minicrits with it.
excuse me for the rant these posts were bothering me