A single person without any family, can do everything he wants in their personal space. That will not harm anyone else. If they do that, earn a living and get famous, that will hurt their family and future generations too. That's why we need law and regulations.
Taking your example of sports: An organized league is something that an athlete joins by choice. The athlete agrees to abide by certain rules as a condition of participating in that league; they aren't being forced to give up their right to choice, they're choosing to.
The comment you responded to isn't arguing against laws and regulations, it's arguing against laws that take away agency for some reason besides protecting equal rights (e.g. someone's swinging fists aren't going to hit anyone else, but "we" don't like that, so we'll prohibit them from swinging their fists, because we feel it's for their own good).
Society shouldn't dictate what's good for the individual; the individual must.
It's not just a bad idea, it's totally immoral and unacceptable. Denying a person their agency is denying the very essence of what makes them human. It's no different than slavery in principle. Either you have self-ownership or not, there is no middle ground.