Every business does this.
Every business. Every institution, even.
Rules are there for a few reasons, but precisely enumerating the things you can and cannot do isn't one of them. (That's why programmers definitely shouldn't litigate pro se.)
One purpose is to try to indemnify the institution making the rules: "See, we said you're not allowed to do X. Damages resulting from X aren't our fault." Another purpose is to deter bad behaviour: if they say you're not allowed to do X, you're less likely to do X. A third purpose is to provide cover for their actions - most easily by writing a rule that literally everyone breaks and then selectively enforcing it, or by writing vague rules you can selectively interpret. If they can punish you and then point to a rule you allegedly broke, you're more likely to accept it and less likely to retaliate. Notice how all of these purposes have to do with manipulating other people. (Are you reminded of any countries?)
You should do it too, if you want to be successful in an amoral business environment. Don't hate the player, hate the game.
Unless your customers pay extra for well-defined rules to create a stable environment for themselves. In that case, you should do that, and take their money. That sort of thing is, for example, why some people would rather pay more for a technically inferior Fairphone or Librem than a flagship Android phone or iPhone.