So tired of this "there are organised groups of reviewers trying to ruin careers". Dear me, if most of us had the power to ruin careers, I'm pretty sure two-bit authors wouldn't be our targets.
Funny how it's "successful word of mouth marketing" when it's positive, but the exact same mechanism in the negative is somehow an organised virtual lynching.
TINC, as we used to say back in the day. There Is No Cabal.
As Usenet has few technologically or legally enforced hierarchies, nearly the only ones that formed were social hierarchies. People exerted power through force of will (often via intimidating flames), garnering authority and respect by contributing to the community (by being a maintainer of a FAQ, for example), or through sheer persistence, spending more time and writing more posts than anyone else (see Kibo, etc.).
Also fuzzy kittens. Because.