Consider an immaginary universe where the following episode happens: You're in a swimming pool and an idiot comes over trying to poop in it. You try to stop him, because...you know why, that's not a proper use of the swimming pool. Plus it ruins your experience, plus makes the day bad for everyone just because the fella couldn't bother going to the public toilet. The guy argues "oh you'r gatekeeping unfairly the swimming pool, I've paid the entrance ticket too." Yes, you idiot paid the ticket, but a swimming pool is not made for pooping in it. I may be struggling to decide if playing with a football in a swimming pool is appropriate or not, but I can definitely say that's not for pooping.