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Although its called "We Are The Music Makers", thats a reference to an Aphex Twin track of the same name and its primarily an Aphex Twin/Autechre/IDM/Warp Records electronic music (and/or general nonsense) discussion board. There is an active subforum called EKT (dont ask) where people discuss making their own music.

I believe there's an unrelated subreddit called r/watmm that is more literally about music making.

https://www.kvraudio.com/ is worth checking out. Some of the very best independent audio DSP devs in the world are there, along with great sound designers, hardware hackers, and a motley collection of music makers.

Depends on what you mean by alternatives. Some gear focused forums (ModWiggler, Lines, Elektronauts, etc) necessarily cover some of the same ground. The Dogs On Acid forum is also still around, though it's changed hands over the years.