I've never used Slack but in Microsoft Teams there are Teams and Channels and they pretty much map 1:1 to Discord's Servers and Text Channels. You cannot leave

I've never used Slack but in Microsoft Teams there are Teams and Channels and they pretty much map 1:1 to Discord's Servers and Text Channels. You cannot leave individual channels of a Team though you can mute them and you have even less permissions than Discord. So maybe it isn't a 1:1 replacement for Slack but it certainly could compete in the field.