Larian did say they would have liked to release modding tools for Divinity 2 (during development of D2:ED it was a hypothetical possibility), given enough given free enough time and resources to devote to that (see the old topic
Is it modder-friendly?). Maybe they've kept that in mind for their next projects, and can develop the tools with the game, rather than requiring another extra chuck of resources when the game is finished.
I think Bethesda has just a tad bit more resources than Larian, and devote slightly more money to advertising (which seems to be the primary factor in game sales).
People will compete for achievement points in a single player game. People will even buy games with achievements that have odd numbers for achievement rewards, so they can get screenshots of themselves with a gamer score of 100000 or 123456789, etc.