You know what is nothing like Slack in functionality and you'd knew if you have used Slack? Most IRCds.

I use Slack everyday, and I disagree.

I've run numerous IRCd's for decades. They are completely stable and scale to 10's of thousands of users per VM. I can't even remember the last time I had one crash. There are already tons of integrations for IRC. It is just difficult to get people to understand the simplistic beauty of IRC. People like "shiny", as mobile phone addictions have proven. There are not many great web front ends for IRC that are secure at the same time as being shiny.