I don't think it was always comfortable (or welcoming) for the LotR people

I love the Silm and Silm fandom, but I know what you mean. I think it can feel like there are high barriers for entry now, as increasingly writers draw on not just the published Silm, but HoME, Parma Eldalamberon, the Letters...not that that's a bad thing, but it shouldn't be seen as a minimum requirement for participating in the fandom. It's only very recently that some of those texts have become (relatively) widely available, and it's flipping expensive to acquire the whole lot.