Tools to prevent information loss in modern Open Source communication?

I have noticed that, mostly for obvious reasons, new OSS projects stopped using IRC, Google groups, forums, mailinglists and even Github for communication purposes; instead I see Discord, Slack and Telegram. While these tools work well, their search capability is awful, but what is worse, at least to me, the content in these platforms stays there and is not indexed by DDG, Google etc. A lot of valuable information is getting lost that way; internals are discussed in detail and disappear when channels are cleaned up, destroyed etc.

What are tools (bots? I could imagine a free service you can have sign up to a server/group which lurks and dumps 24 hour archives to HTML), alternatives and ways to reverse this process? Or does no one else see this as an issue?