<…> First, you need to be popular in this forum.
Not really, at least not to the extend you are inferring. I’d say that the foremost element is content alongside a reasonable perseverance, although many factors weigh-in (content, placement, time, topic, how worn down the topic is, lovers, haters, groupies, in agreement, in disagreement, informative, novelty, etc.), one does not in any case become popular by doing nothing, but rather through posting on a decent enough level.
Also gaining merits was like first come first serve, look at all the first pages of the topic. Merits were given to those first commentors unlike on the second page, third page and etc .. you can rarely see merits from that pages. Maybe because this pages was not like that important to read and also the readers were lazy to give their attention.
I analyzed that quite some time ago (see
Forum Merited Messages- Does size count?), and since it was pretty early in the Merit System era, I expect things to have shifted a bit since then).
Regardless, I’d say that topic starters often have put quite a bit of thought behind, and are therefore merited more often due to that fact (providing the content is decent enough). From there on, after a certain amount of posts, it is common for answers to sway off-topic and/or be rather repetitive, which leads to the later answers to be less merited. There are obviously exceptions, but you we can’t generally expect too many novel on-topic informative answers as the thread spins on.