OP, who exactly are you accusing of giving merits to their "friends"?  From what I've seen, it's mostly the shitposting bounty hunter families that do that, and a lot of those idiots have been tagged.  Those people wouldn't dream of giving merits to people who make posts that deserve them.

How do you know who merit sources are "friends" with anyway?  You're making the accusation, and I'd like to know exactly what you're talking about.  I'm speaking for myself here:  I don't have anyone I could call a friend on bitcointalk.  I've never met anyone here in real life and I don't exchange many PMs with members other than shitposters asking for feedback removal.  It's not exactly a tight-knit community where Legendary members go out for beers after a hard day of smacking down spammers. 

Seems to me that it's possible that someone might like a handful of posters in particular such that they get the most merit from that someone.  For example, Foxpup has given me quite a few merits, but I have no idea who he is and I've never so much as spoken with him via PM.  There's nothing going on between us behind the scenes.  He apparently likes a lot of my posts, and I think that's probably true for a lot of the cases that you think are gangs of insiders sending merits back and forth between themselves.