My advice is below.
To apply here, applicants should have below-average merits according to ranks.
To Members: 9 Merits
To Full Members: 90 Merits
To Sr. Members: 225 Merits
To Hero Members: 450 merits
To Legendary: 900 Merits
It's just my advice; maybe some +/- would be fine.
However, it seems to me that even with such rules, the majority of users will ignore it and after two or three pages, we will again be overwhelmed with congratulations and unrealistic expectations from here when it comes to merit. Someone expects that he will get more merit here than he managed to earn natively.
Inasmuch as there's actually sense in what the poster said, first we need to be reminded that someone placing an application here doesn't really guarantee that they'll get the desired merits to rank up HERE, it's more of a 50/50 thing.
And then again, if someone has been able to earn up to 75 merits on his own, why should he feel lazy because he got help receiving 25 more merits ( from his merit worthy posts). Most of the applications here didn't get all their desired merits to rank up HERE. besides, the whole idea of this exercise isn't just about earning free merits to rank up I believe, it's more about making other to take a look at your posts, access them and merit whichever one they feel is worthy.
Again, getting to the next rank isn't supposed to be the final destination for a user, but a starting point to aim for greater height (next rank) Hence I see no reason why getting to the next rank would make them feel reluctant or stop contributing to the forum as they've been previously doing.
This is just my honest opinion on this, and I'm not saying this simply because I'm close to 75 merits as many would think, no, that's not it at all, because whether or not I send in an application here, I know fully well that I'll be able to earn the required number of merits for my rank up to FM rank.