Yeah I'm not saying that 100k is definitely enough to get her removed or anything. But if 100k people saying "this sucks" is meaningless, imagine how much more meaningless just quitting and saying nothing is.
I'm not saying that these people will accomplish their goal. But they're definitely stirring up bad publicity for Reddit. That's not a great way to get a CEO fired, but bad publicity is a lot worse for Reddit than losing 100k users.