If companies terms of service said “we can do whatever we want whenever we want, and we don’t have to promise any service, and you have no rights” nobody would sign those terms.

Nobody who took the time to read the terms of service, and who felt that there was a real risk of those terrible terms being invoked, and who felt they had a viable alternative. But for the other 99.9% of people, they will just hit agree and move on.