A new beta release for the Steam client includes scoped-achievements.
Achievements can now be split into game mode specific, DLC specific and seasonal specific achievements.
In theory, this will now allow players to achieve achievement completion, even though they’re not interested in the multiplayer aspect of a game.
Depends on the game. Skyrim, for example, doesn’t always give a reward, especially for the main quest objectives, it only advances the plot. And Team Fortress 2 is one game I know that gives item rewards for achievements.
Achievements dont advance the plot either so why care about meta collectibles?