[whunting]

I dont believe that. Its open for anyone to read, and for math PhDs to quickly register. All other addresses are put on hold for manual check, not rejected. Some people have requested to join in this thread and have received an account without a PhD. Its not meant to be elitist at all, just focused on the quality content (wherever it comes from)

[elihu]

In the "user guide" it says it's a platform for math/stats PhDs, and describes a process for checking email addresses. It certainly gives the impression of unwelcome to people who are neither PhDs nor currently enrolled in a PhD program.

If you want people who don't have and aren't trying to obtain a PhD to participate, I think you should say so explicitly.