rjbuffchix: GOG has de-listed other games, why is this one so special?
It has a lot of players, and it still gets massive content updates, mostly pure single player content.
...what is apparently a DRMed game, ...
That's stretching the definition of DRM. DRM would mean they could take away content from you. Like Steam locking your account, or forcing updates on you that cripple soundtrack or censor games for your region.
In NMS, on the contrary, once you have "unlocked" the content, either by playing online or hacking the save game, it's yours to keep. I don't see any "Digital Rights Management", just a stupid decision to lure players to "community content" with something which offline players also want to have, and which they could have without breaking the game for anyone.
Games having content broken up into numerous DLCs has not become the norm for offline single player games? It certainly has become widespread, far more than it was in the pre-Horse Armor days.
Paid, purely cosmetic single item DLC has become common for single player games? Well, I don't have a Steam account, so I have to take your word for it.