Yes, but I can’t link to that discord discussion 
Absolutely! And that is why I pointed to various contribution guidelines for Rust. I believe that they have manage to “enforce” a culture of openness by redirecting all flow to Zulip from all documentation. Same for Lean.
Even the governance model of Rust has explicitly one Zulip channel associated with each team. These Zulip channels are open to anyone. Of course, they are mostly used by the team in question, but I have created several topics to the operational semantics team channel to ask questions and always found a quick answer. Because the t-opsem team monitors that channel.
Similarly, OCaml could attach a Zulip channel (or again, anything else, as long as it’s open and externally referenceable without account) for e.g. dune-devs, compiler-devs, editor-devs, stdlib-devs, and working groups such as wg-modular-implicits, where discussion would be redirected. Importantly, these groups would be referenced by the contribution guidelines of each of these projects.
In contrast, I was looking at modular implicits and found a discussion from last year with this message:
I could not find where said discussion happened It does indicate that, sometimes, synchronous discussion is needed. Ideally, this message would contain a link to that discussion, and I would feel like I could take part. Reading this, I think this interaction could have been slightly frustrating for Eduardo.