Terms and conditions are weird, because by and large (in the US) judges have determined that they don't really let the companies do anything that they wouldn't be allowed to do otherwise (except I guess forced arbitration), but they keep filling them with borderline illegal requirements and litigate them line-by-line when it comes up.
The main thing is any company can start denying you service whenever they want as long as it's not for a protected reason, and then it's up to you to prove in the court of law (or arbitration) that they didn't specifically screw you over in any particular way, which is usually not worth the hassle.
The main thing is any company can start denying you service whenever they want as long as it's not for a protected reason, and then it's up to you to prove in the court of law (or arbitration) that they didn't specifically screw you over in any particular way, which is usually not worth the hassle.