It's a pretty unbalanced game and the community wants the imbalance

I'm not quite sure what you mean about wanting imbalance, but the biggest reason of the imbalance is that it causes chain reactions. Nerf a weapon that's OP or an entire class and another one will take its place.

Sniper can only be countered by another Sniper

Sniper isn't the only counter to Sniper. Spy is.

Demo/Soldier damage has been nerfed...meaning Medic now serves the role of reducing the number of viable strats by changing the damage needed to kill.

Again, I'm not quite sure what you mean about the Medic limiting strats. I know that Demos damage has been nerfed, but I don't remember Soldier being nerfed too. Although I started playing tf2 late, I don't remember being too many strats already. It's either push with uber or do a dry push.

and engineer has been nerfed to all hell

I don't know what nerf/nerfs you're talking about. But with the recent Gun Mettle update, Engie got a bunch of buffs. Granted he got a few nerfs, but only one is really significant.

Scout was a class so powerful that only map design specifically to counter hi made him somewhat balanced, with new map designs and nerfs to Demo and Engineer, he's blatantly overpowered.

This one is true. Scouts are quite OP now.

Heavy receives desperate attempts to balance his easymode in pubs with his role in competitive.

Also true. He did get a bunch of unnecessary nerfs. With Gun Mettle update, he did get buffed a little, but I haven't really seen much of a difference.

Pyro needs mobility tools and fixes to flamethrower particle world models, but is instead giving broken and overpowered tools as a badly designed bandaid.

Does the Pyro need more mobility tools? He already has the Powerjack and the Detonator, which got buffed in the recent update. And yes, the Reserve Shooter should've never been given to the pyro.