Let me also add an interesting thing I have seen recently in Decision Making 2.0! (1.0.1?) - #23 by matklad — the sheer list of potential place for discussion in the Rust community.
I would say historically the Rust project tried to organize “one true venue”, but that didn’t pan out, the current state is more of a product of accidental historical factors, rather than intelligent design (some may recall that Rust move off to discord off the IRC, but then it somehow end up using Zulip. Today, I also feel that the internals discourse isn’t really any more “the place that matters”, but there wasn’t an official deprecation).