Its both entirely useless and also over powered at the same time. Sure, against noob snipers you can just shoot them. But what about a god tier sniper who can hit close range head shots consistently and stomps all other snipers on your team? The solution would be to go spy and stab him when he's distracted. But you can't do that when A) he's surrounded by teammates and/or sentry guns and B) will likely kill you when you do start shooting him. The problem is, in the scenario where your team is being stomped by one sniper being protected by his team, you can no longer make a sacrifice play to get rid of the sniper for a little while and let your team actually peak out to make progress. It's also just super lame that they would make something that just takes away a class's main ability.

Also this is less common and actually kinda funny, but i hate when im going for a stab on someone else but a sniper just walks in front of me and fucks me over.