Confluence is helping us move away from email, but we can't do that without having confluence integration with Slack to notify users that a user has been mentioned.
The problem with notifications inside Confluence is that its not a tool that is open throughout the entire day. Notifications might only be checked once a week and I would miss out on docs that need my attention (I miss out on reading the mention). However if this is linked with slack, then I can see it on my slack message on both desktop and mobile when I'm on the go.
Happy for you to reach out to me to understand my use case further, can help with any testing efforts too.
+1 for Data Center. This does nothing to support enterprise customers on Data Center.