In the firearms community, a lot of shooters keep their spots on public land a secret because other well known spots have been closed off or prohibited from being used for target shooting because idiots trash the place or use it unsafely.

In the urban exploration community, people keep the locations of their abandoned or secured buildings a secret because a lot of people would come and steal stuff or trash the place which attracts more security and potentially dangerous encounters.

It sucks but it’s understandable. “The tragedy of the commons” is often invoked for eugenicist reasons, but the concept is real, but only when your society is never instilled to care about their environment. Many communities and countries don’t have this problem - America does because, well

But I don’t think your example is gatekeeping. Anyone who’s withholding the location from you is going to do so even without the sign.