You can't be more than about 10 years old if you think the "entire history of computer games" only launched feature complete games.
Motherfucker, RETAIL BOXED RELEASES IN THE 90's would have shit added on after publishing. The only difference is that you didn't get regular patches that added new features, you had to wait until the expansion pack came out. Online multiplayer games where you couldn't play with anyone that had newer map or character packs. Shit that would be a minor update now used to come out as full price releases.
Hell, if a company released a "sequel" that had as little new content as Doom 2 did compared to Doom they'd be fucking crucified. "WTF, man, only like 30 levels and two new enemies? BUT MODDERS ALREADY MADE MORE LEVELS AND ENEMIES!??!?"
"Games only released feature complete!" - Someone that has literally never played Starcraft, Diablo, Unreal Tournament, Doom, SimCity, Duke Nukem 3D, or literally hundreds of other games I can't be arsed to list.