The functionality of achievements as transparent telemetry seems entirely accidental, but may be the most valuable aspect of them. Now a developer can look at

The functionality of achievements as transparent telemetry seems entirely accidental, but may be the most valuable aspect of them. Now a developer can look at similar games to the one they're developing and see what filtered players (although it won't tell them why it filtered players, since 'too difficult' and 'boring' look the same in the stats). They can see what endings were popular (which usually translates to some measure of popularity score for characters, factions or whatever. That kind of info is usually traded behind closed doors for extortionate sums.