I had to use the Wayback Machine to dig this up:
> 7 Nov: Anti-procrastination features
> Like email, social news sites can be dangerously addictive. So the latest version of Hacker News has a feature to let you limit your use of the site. There are three new fields in your profile, noprocrast, maxvisit, and minaway. (You can edit your profile by clicking on your username.) Noprocrast is turned off by default. If you turn it on by setting it to "yes," you'll only be allowed to visit the site for maxvisit minutes at a time, with gaps of minaway minutes in between. The defaults are 20 and 180, which would let you view the site for 20 minutes at a time, and then not allow you back in for 3 hours. You can override noprocrast if you want, in which case your visit clock starts over at zero.
https://web.archive.org/web/20100414160040/http://ycombinato...
Even Hacker News acknowledged 15 years ago that it was a social site and that social news sites could be "dangerously addictive". The goalposts for defining social media keep moving as people try to avoid any definition that captures their own internet usage, but I think it's important to be honest about what we're all doing here.
Also the noprocrast feature is still there right in your profile, though I don't know if it's documented anywhere.