It seems a number of us have been pondering this phenomenon for some time, I also have been thinking of starting a thread along these lines. As people have pointed out above this is a multi-pronged nostalgia: nostalgia for our childhood and youth where we automatically had a greater sense of wonder, nostalgia for the pre-web era (could even be early web era too) where information was much, much more limited, slower moving harder to find and finally, nostalgia for a time when these old cases weren't quite so old and hadn't been debunked or at least seemed more possible.
All of this ties closely into Hauntology, with people's sense of wonder/the uncanny/the Weird in their own childhoods and in the media of yesteryear. No wonder people whose childhoods coincide with this era (mid-60s to early 80s?) and even those too young to remember this are looking back to it for sense of wonder. The recently invented not-quite-genre of Folk Horror seems to be part of the same phenomenon too.
This partially explains the malaise the board is in, I'm in my mid-40s and as far as I'm aware, one of the youngest people here. Again, as has been posted, Creepypasta and the like are very alike IHTM type cases. I remember someone somewhere on here posting back in the early 00s that IHTM stories had a "fictional" feel and that the poster was wondering about starting a thread of deliberately and openly "fake" accounts to see if this could be replicated. I don't know if anything came of that, I think it would be all too easy and pointless outside of a creative outlet for people. Many of the more elaborate IHTM accounts are almost certainly fiction, there may be ghost (pun intended) of truth to them, but that's all, this subject came up recently, prompted by this fun but almost certainly made-up story:
https://forums.forteana.org/index.p...es-from-reddit-other-sites.47527/post-2175715