Put yourself in the position of someone in the third round of a tournament, loser's bracket. I'm sure we've all been there before. So this time, you meet up with your opponent, and you're doing fine until they play you into their grab. You can't get out of it, and your damage meter racks up until they smash you off. You wonder what the hell just happened. Then it happens again, and again, and again, and you get 4 stocked. I imagine you're very frustrated, but after another round of this, you have come to accept that they have mastered wobbling and you can't do anything about it. So, you accept your loss and shake hands with your opponent, wish them good luck, and go sit down to play friendlies somewhere.
On a personal note, I would feel ripped off. Wobbling is hard enough that anyone good enough to do it consistently against me is probably good enough to beat me anyway. I would want to have a good match, and be beaten in a real match. Moreover I don't want people practicing wobbling so that they can beat people. I know that people practice for tournaments so they can prove themselves worthy players, and I would feel bad if someone had spent their time mastering wobbling and nothing else. It's happened before.
Finally, I don't think anyone genuinely needs wobbling to win. Playing your character intelligently is far more important in the long run, because if anyone's mental game exceeds yours, they probably won't be letting you grab them.
Wobbling is frustrating, and annoying, and although this is a somewhat personal decision - banning the tactic, that is - I feel that I'm being fair to people this way. If anyone doesn't understand that, I employ you to put yourselves in the shoes of someone I described in the first paragraph, and to try to understand why wobbling could make a tournament less fun for someone.
Everyone wants a good, real set, so one thing I'm doing to help this tournament be the best it can be is to enforce the probability that everyone gets one.
We never actually got to play or talk Grmo, guess I'll have to come down for the next Brawl tourney instead.