I thought so when I started at a company that had that policy but in the end we still mostly ended up with split-brain issues (eg some information is shared in both places, some in only one, some updates get lost) with the added negative that stuff disappeared from Slack.

It's just a hard problem overall when you have email, chat, wiki, docs, and a ticketing system.

And, unfortunately, all these things exist because not one of them is actually good beyond its scope (if it's even good within its scope to begin with).