Riot has inline Markdown, so I'd argue it's actually superior to Slack for serious work.

I've used Riot as a Slack replacement and setup notification bots. Its effective for the task and I could use the IRC bridge for a similar function.

Only reason I moved over to Discord was too many chat apps and the hobby users were all on Discord anyway.

Riot is more slack-like than whatsapp-like. We use it at work instead of Slack now.