It's just an option if you don't want to deal with port forwarding, dynamic ip numbers and all that. The game can also host multiplayer through Steam invites or you can run the command line server app on your computers at home, it's extremely light on resources.

i cant get in on a server to play with others cuz they all have keys it gets tiring playing by myself that is one reason why i stopped playing

Yeah, there's very few open public servers because the game has zero defenses against cheats and griefing. (Just digging a bunch of holes can be enough to render a region unplayable with lag.)

The multiplayer is very much a co-op exploration with friends and family kinda deal for now.