Well I know for 4chan, each thread is ephemeral and depending on how active a board is, the thread will be deleted. Which I think is the challenge citing it. Since even a day or two after finding it, it can be lost.
Does that even work on 4chan? On /b/ threads can vanish in less than an hour. There used to be specialized sites such as 4chanarchive to fill the gap, but last I checked most are dead.
> "And you have things like the internet archive or Webcite[0] to make sure the web document doesn't disappear."