If everyone quit tipping at once, yes, that would mean immediate, dramatic change. But that is unrealistic. And some people not tipping in protest when it is expected while most continue the tradition is the worst outcome for the workers. It makes their material conditions worse but not to the point of achieving anything.
It works both ways. If noone tips then noone will work at restaurants where their wage consists solely of tipping. That is also how capitalism works.
If everyone quit tipping at once, yes, that would mean immediate, dramatic change. But that is unrealistic. And some people not tipping in protest when it is expected while most continue the tradition is the worst outcome for the workers. It makes their material conditions worse but not to the point of achieving anything.