The point is also to minimize potential damages caused by a bug in the software. Just this year there have been multiple data-destroying bugs in publicly released software. If the app runs as a server it’s usually trivial to have it run as a dedicated user, with just enough permissions to do its job.
It’s just good practice, even though the risks might be low why risk it at all?
Lots of modern indie or AA games are cheap and really, really good.