* channel services can provide archiving and notifications.
* scrollback can be handled by a bouncer, yes, but it's up to the IT dept to set it up per-user
* there are plenty of usable irc clients for mobile, web, and desktop to satisfy this need.
source: Started using telegram/slack but productivity went down so work launched an internal ircd (inspircd). Internal wiki, git, and sharepoint for documentation/files/code where it belongs. Not the chat client.