It is just that merit is used to make this forum to have quality posts.
Merits cannot be fully considered as the certain way to ensure quality posts.
I couldn't agree more with some of your points, because I have come to understand on my own, that more merit is often in a direct correlation with ones quality input or amount of merits gained overtime.
Just as you said when one has more merits, it's easier to simply add just a few more, compared to very low merit score(likes) trying to get more to become recognized.
Just like I have said before, merit system has been the reason we have quality posts on this forum. If merit system was it introduced, this forum would be a place of trash posts.
You can someone not posting as good as another person, but having more merit, but still he is having merits and ranking higher. People that are giving merit can be partial, especially those on local boards, but merit still ensures that posting quality on this forum is achieved.