I'm against nerfing Tobi not just because I use him but because in general he's one of the few ninjas that you can grind for that's even remotely close to the level of ninjas you can only access by paying a lot.
No I'm very far from winning every time with him. I've lost at least once to every main even without a power gap. Sometimes even with a power gap.
It's actually very easy to build a strategy against him. Just take the time to read his skills and understand them and you should be able to figure out how best to deal with him.
And of course there will be teams that don't match very well against other teams. It's kind of the point. There isn't gonna be a single perfect team.