Mr.Mumbles: Cool.
I've never really played enough to get that far where I could actually run into any other people - it's more or less been sitting in my backlog for a long time - so the whole multiplayer aspect was kind of lost to me especially since I know the version here was GOG-only before.
Now I'm curious to see whether it can still be played completely offline if one so chose... Either way, I'm thinking of properly and finally delving into the game rather than just repeatedly pottering around in the beginning stages.
There is a social hub you can access once you're clear of your starting planet. There is a multiplayer currency called "Quicksilver" you can earn by doing missions from the hub that can be spent on cosmetics (and void eggs, which eventually hatch into living ships). This part is the only thing that "needs" multiplayer being enabled.*
(* = Quicksilver is saved locally, there's a very comfortable savegame editor available on github, so if you're just after the cosmetics, you can have that solved within about 10 minutes of suffering the presence of others...)
You can turn off multiplayer in the options, or at least configure the interactions to a degree where no one can bother you (which includes muting strangers, turning off player-inflicted damage and disabling editing of your bases by anyone but yourself). You can even set exceptions for people on your friend list, so it's not like you're being tossed in a pool of rabid, foul-mouthed piranhas (like, say, pretty much any game with PVP focus). The community is usually pretty chill, and I do occasionally spend evenings handing out goodie packages to new players in the anomaly.
Outside of the anomaly, the chances of encountering a player in the wild are astronomically small. Even close to the center, you'll find some more-or-less abandoned bases at most, and once you progress beyond the first galaxy, chances get even smaller. It's pretty lonely out in space. ;)
