Kind of sad to see slack communities slowly die, as the message archive for free slacks gets reduced. So many empty channels, with history lost.. Yet the communities are unable to move to anything else due to a mixture of company policy (alternatives are blocked at many workplaces), lack of agreement on where they should move, and general inertia / absent administration.
I also built this tool that any Slack admin can use to download their archives into a static site: https://github.com/akkartik/foc-archive. It's not as polished, of course, but the code is pretty tiny and your data stays in your control.
Yes offline archives help but the lack of in-conversation context/long-form conversations, and wasteland of empty channels is still not healthy. The semi-private nature of slack discussion means putting history on the open web is out of the question too, so needs some fiddling to get authentication working etc.. There's no easy way out of this situation really