I used the "step" language because people on the Internet are depressingly literal, and if I just called them a utility monster, someone would tell me that since they're clearly not demanding I spend infinite resources on them to increase their utility, they're not really a utility monster.

If everyone in society gets to do that, even with a few free-riders, everyone ends up better off.

No, they don't, because conceding to such demands affects motivations. With the number of free riders we have now, giving in to everyone's demand isn't going to cause too much damage from giving in to the free-riders. But that ignores the role of giving in towards making more free-riders.

Also, remember that we're talking about someone asking you to turn your noise down even though your volume is already within what is allowed by regulations or social norms.