It seems Slack has taken to close down public rooms that
too large ( 7000+ people it appears). Just this week, the
Reactiflux Slack was informed that it is no longer allowed
to grow, and has since decided to move to Discord instead.
I understand why Slack is closing down large rooms, as they are an obvious drain on the profits of the company. But I think they underestimate the value they provide. One of the reason I push for Slack at work, is that I can use the same tool to talk to my colleagues as I use to find help online, and for social matters. If this is no longer the case and I have to use IRC or Discord for public chats, and Slack for strict business-talk, the benefits of it shrink in my mind.
We will see what the future of Slack is. I just want one chat app I can use for everything, and it seems Slack might not be it either.