> I really don't believe "The site owner decides what you can and cannot do." statement. What is the base of this? This does not seem to apply to anything in the real world.
It kind of does though; if I own a store and say that only people with hats can enter, then I'm free to do so. Silly? Yes. Legal? Also yes.
There are some circumstances where it's not legal, mostly centred around discrimination. Details on this differ per jurisdiction, but generally speaking you have a right to refuse customers.