The problem with this is that you need to be at least a Moderator to give a merit. With every single game developer a moderator, one could just wreck the forums if they felt like it, and there's tons of non-meritworthy spam comments on every game.
Although there could be, in the future, just that one privilege given to developers... I haven't ever seen this suggestion before. Spread the word.
Graham, I didn't suggest make every developer a moderators. I suggested let the developer of a game be able to hand out merits for comments on their games.
What's wrong with your idea is they could just give merits to people who like there game or say good things about there games while a person with a great comment who does not like the game will not get a merit. It would be to easily corruptable.