For me I primarily come back for the high quality fanfiction, as well as the occasional translation.
There's a lot of high quality stuff here even if it doesn't get quite as much love, and I've come to the point where rereading high quality fanfics that are old is an enjoyable experience even if I know they will never be completed such as Elf's various works.
There's also just a large source of Nostalgia that comes with it, I first joined in 2011 and it was one of the first forums I ever joined and by far the one I became the most active in.
In 2011 I was 16 years old, and now I'm 27. I've gone through a lot over the years and changed a lot, so it's interesting to look back at a digital record of myself back then.
It's one of the reasons I always love making accounts, writing down my thoughts is always something I enjoy and sharing them is often also enjoyable. One of the strangest experiences I've found is vehemently disagreeing with myself, it's an experience that always reminds me of just how limited our perspectives are at all times, something I find useful as a stubborn individual who forms opinions easily.