I suspect that what they do is that they game the algorithms so that they can insert their hit before the actual content, the way it's weighted currently makes

I suspect that what they do is that they game the algorithms so that they can insert their hit before the actual content, the way it's weighted currently makes it possible to get sites with links to content to rank higher than the actual content, which is wanted in some ways (like the HN discussion is an important complement to what it links to) but with the spam sites it's just littering down the interwebs.