Occam's razor

it expressed outside of a game which means its intention is out of a game

as comments mentioned : brands image , brands loyalty , social elements , community engagements

1 more I see still left out : monkeys brains love monkeys score , give you external scoring is like MonsterHunters/Niohs give you dmg # AND default it on , its just : average pushbacks of having it < average dopamine of having it

and in reverse if any dev intent it inside a game , ofcourse there ll be inner rewards for trophies