[geodel]

I guess similar reason Restaurants' customers are referred to as guests.

[tobr]

Huh, not really? A “fan” is an enthusiast or admirer. It implies a certain type of relationship to the thing you are a fan of.

I don’t know that “guest” implies anything similar, it’s just a visitor.

[imgabe]

Guest implies that you have been invited and expect to receive hospitality from your host. Visitor is just someone who showed up somewhere.