Being active is easier than being high quality, and that's why the merit system is partially good, it reduces spam and creates a more challenging metric to rise in the forum ranks. The partially bad part is that it introduces politics to the ranking process, as now ranking up doesn't just depend on quality, but also other people's discretion. The other negative is that it also helps account farmers who have been farming for a long time (especially if they control merit source(s) or a large amount of merited accounts).

I think the question is different for each person. For some, a "self-made legendary" is someone who just spammed in a gambling thread being merited by their buddies/alts or the wall observer thread. For others, it was a long time of high quality posting and activity. There is no definitive answer, each case is different.