To be honest, those accounts in those pics don't convince me of anything. Most of the frequent posters from those domains post plenty of other links to other sites. They were created years apart. Two of them seem to post extremetech.com and/or geek.com exclusively, but posts are 5-10 days apart.

Isn't it a lot more likely that these are simply people who happen to read enough of those particular sites and post to HN to turn up on in a chart like this?

There's not enough data points to point to any kind of concerted effort by these sites over the span of years.

And even _if_ that were the case. Suppose someone affiliated with these sites is posting 1-2 links a week, that's hardly flooding the system. There's still the voting system, right? Good articles float towards the top. The new submissions page isn't jam packed with dozens of articles a day from these sites, is it?