Add to that: most comments will not be seen by a merit faucet. Even if there's a particularly good post, most people will just move on and not even think of assigning merit points.
Not true. Merit sources are viewing all comments on all sections of the forum (I hope!).
If you see a particular comment you feel deserves merit, feel free to leave some.
Ran out of sMerit? You need to be more particular with whom you give merits to.
Or make good quality posts to gain more sMerit.