In my personal opinion, TF2 is a 99% perfect game. The 1% imperfection is sniper. Even Fortnite nailed their sniper mechanic by making it so that it takes a little more thinking than just sitting 10 miles away and clicking on a head.
Sniper sucks, he can instakill you from 10 gazillions miles away without you having any chance of fighting back. Anyone complaining about pyro when this piece of trash exists is being delusional, i'd rather get spawncamped by an ubered phlog pyro on dustbowl than having to fight a sniper once. Only thing people (and by people i mean F2P that haven't played the game for more than 15 minutes) will tell you is to avoid the sightline as if avoiding sniper sightline wasn't just staying in spawn. As if instakilling from any range wasn't enough, you wouldn't dare come close to him since he could instakill 7 of the 9 classes with a good old random melee crit, or just use his smg, seriously who thought it was a good idea to give the long range overpowered class a decent secondary for close range combat that's literal ♥♥♥♥♥♥♥♥. You shouldn't just have to hide behind a wall until you have an uber to play the game it makes you feels like minesweeper is an actual godlike game compared to the TF2 gameplay of hiding because someone can click on your head from 10 miles away.
As someone wise once said : "I really hate sniper, i don't like having a massive field where i can just be one shot by a semi competent sniper player who i couldn't even see, so many killstreaks have ended when i was at full health just a second before just because some sniper on mars clicked on my head after waiting 0.01 nanosecond, the only counterplay is being pocketed by a vaccinator or staying in spawn, at least spy has significant counterplay and requires skill. sniper is easy and thats an understatement"
And to be honest, anyone thinking sniper is anywhere close to balanced has never player one game of casual harvest
People complaining about pyro's airblast are a literal joke, okay he denied your uber/reflected your rocket but at least you get to live, or at least to see him and fight him. Sniper will just instakill you without you being able to do anything, what's ♥♥♥♥♥♥♥ worse than instakill from any range? How can people complain about pyro's airblast or spy's kunai when sniper exists?
What i'm saying is, don't complain about any type of mechanic in the game as long as they're not being instakilled from across the map.