thanks for explaining your position
1) only 10,000 message search history on the free tier
2) the threading implementation is an abomination and wouldn't work for typical DDF usage
3) not public
4) it's not meant to be a replacement for forum style communication
5) it's not self hosted and migration of existing users will be a complete disaster
6) existing DDF content will be lost and/or fragmented
These are the first 6 reasons that came to me. I've been using Slack daily for more than 5 years, I can tell you emphatically that Slack is NOT a replacement for DDF.
It's probably a good alternative to alI of y'all's DDWhatsApp groups...