Does anyone adhere to the guidelines? Apple doesn't, and they even have the ability to change them. They're guidelines, which if you look up the definition are not iron-clad rules.

A guideline is a rule, just a non-specific one. Sometimes it's more a suggestion, sometimes it is iron-clad. For example, HIPAA Privacy Guidelines will still land you into serious legal trouble if broken.

The fact that Apple are rejecting apps that break the guidelines (even if not consistently) is proof enough that guidelines can be iron-clad rules in certain cases. It depends entirely on the context and the authority setting them.