Proof of effort.
I see a lot of posts in meta section moaning for removing merit or merit is not fear etc etc. Seems like they are trying to say, receiving merit is Impossible. Sure it's not easy but it not impossible, it's just difficult IMO. Guess what(!), it was suppose to be difficult or spammers would be receiving it very easily with their one line/ few words "thank you", "very good project" etc. type of posts. It would not have any difference with activity count.
Well it's probably almost impossible to achieve a high rank if you can't speak English or articulate yourself very well. People got used to just being able to rise through the ranks by merely posting whatever generic posts they could be bothered making over time but that was the problem. You could literally have as many Hero accounts as you wanted just by logging in once a day to claim a giveaway and 1.4 years later you'd have an arsenal of Hero accounts farmed to do what you want with. Now this isn't the case. Not only will you have to put effort into your posts they also have to stand out enough to be merited which isn't as easy as it sounds.