How are any of these OP at all?
They ban most weps just to be as standard as possible, only a few weps in the game can be considered OP (Tomis, Gru, FoS, Sandvich, Sandman, Mad Milk, WRANGLER
lol
Wrangler allows you to beat every overhealed class in a second.
Tomislav prevents the Heavy dying from ambushing, one of the last ways to kill the Heavy that hasn't been countered with another stupid unlock.
Sandvich turns your 450 HP Heavy into a 600 HP Heavy. There is literally no way to beat a 600 HP Heavy/Medic 2v2 without Snipers/Spies involved. Good Heavies don't go into long open places for Snipers to shoot them, and you can mod your decloak sound so you can hear Spies fifty miles away. Also, Tomislav is best spychecking weapon that isn't a flamethrower.
FoS lets you wade into the middle of combat, drop your Sandvich, and not give a fuck about anything while you point-blank Minigun everything to death.
Sandman is a free kill every couple of seconds.
Mad Milk allows you to take on a Heavy and win, 1v1, without any dodging involved.
Wrangler allows you to beat everything 1v1. Everything.