I know and agree with what you say.
A couple of things to note.
I don’t suggest Mozilla Matrix but https://app.element.io/ where you can just enable notifications for certain users who are interesting for you. It is also free (AFAIK) You can also move your conversation to a private chat for particular topics. I am also open to alternatives.
I suggest this because I generally see people try to communicate actively about different projects under irrelevant topics. This would enable real contributors to communicate on what matters. Also it makes easier for people working on similar things to find each other as @georroussos underlined.
In order to prevent noise, we can be explicit about the use of the chat, being only for development and project-specific purposes.