Slack does not even scale to corporate size, instance sizes are too limited. Also, they have no corp sales plan to speak of.

Finally, wrong kind of comms - chat is ephemeral, and messenger is only a small part of what is needed or corp facebook offers. And Slack is lacking the necessary controls for a corp environment.

> Slack does not even scale to corporate size, instance sizes are too limited. Also, they have no corp sales plan to speak of.

Your information is outdated. Slack recently introduced an Enterprise product (on-premise AFAIK) where you can have multiple workspaces for each division, but auth is managed centrally and organization-wide channels can span across all workspaces. We're using it at SAP.

> Slack does not even scale to corporate size

I don't understand what corporate size is. Care to give some numbers?

Upwards of 20.000 employees in my case here, with some serious variance and fluctuation because of the work being seasonal.

We have ~50k active users in our corporate Slack.