The problem is that people are completely skewing the actual issue -- I don't think there's a lot of intentional bribing and such going on, like "Hey, here's some money, write a good review.". It's probably more like "journalists" know developers or representatives from the publisher or developer of the game they are writing about, and feel more inclined towards talking positively about it.
However, I don't think the representatives or developers have any special training in deception and persuasion, so if the publishers or developers intentionally order their employees to "get to know them", the journalists would probably find out about that really quickly through their behaviour. So, it's unlikely that they are "faking" their relationship just to increase the odds of a journalist writing positively about their game.
I think that, since they hang out in the same circles very often, they are probably just friends, and as such, the journalist friend might feel more inclined towards writing positively about their "friends" game.
Like, the representative of the publisher or developer would most likely have a positive bias for a game his or her company makes, and unintentionally try to push that bias onto her or his friend. The journalist friend of the representative friend would have some positive bias for his or her friend regardless.
It seems like, in most other circles, the journalists/reviewers are more like their own team -- as in, they hang with each other, or, to exaggerate it, in an "us (critics.) vs. them (movie makers.)" situation. The games industry blurs the lines.