Researching backlinks from some of the largest/most-heavily trafficked sites, I've noticed where some are involved in widespread practices of creating what are obviously their own privately held/managed/directed link pages. These are pages having blatant, lengthly, exclusive lists of links back their own pages. Talking 50 to 100+ links one after the next and some times much greater than this. Some without even the pretense of any textual content.
I have thought there were penalties for partaking in this sort of thing.
I have also thought that G. at times writes out exceptions for sites of a certain age, past reputation, and other parameters that I'd rather not mention.
What is going on here? Are there rules that only the majority of us have to follow?