I don't think a proprietary forum that requires an email address to view information is equivalent to lemmy. It's publicly accessible, open source, and can be federated. Matrix still requires some kind of account to view information if I remember correctly.
Sure, but that’s not the only problem with discord as a documentation. I’d argue, from a practical standpoint that that’s not even really a big problem. The problem is that a stream of random conversation, sprinkled with memes and jokes, with multiple parties having a chat is the absolute possible worst way to find information (and it’s not even guaranteed to be there if someone hasn’t asked; or maybe someone asked, but never got answered)
While I think its a huge deal to require email addresses for publically accessible information, the rest is true. Although, upvotes and and different posts can help cut a lot of that crap. Also offers the ability to be indexed. I personally still throw the word reddit at the end of a search if I really can't find anything and one of the top comments usually has what I need. I agree though, not perfect or optimal for the task, just better than discord.
It's possible to view matrix rooms without an account, but it has to be supported by the server as it has to load the conversation history from other servers over federation before showing it. I'm not sure about how long this currently takes.
I think the key is whether it's indexable by search engines and can be archived by archive.org. Any chat service fails miserable at this and is thus not acceptable for documentation.
The problem is the fact that the documentation exists solely as a series of what are effectively chat messages, not what platform those chat messages are hosted on. Markdown files or bust.