>it misses practically all of what makes Slack so popular - UX
I strongly disagree. Slack has nearly the same UX as every chat platform of the past 2-3 decades. It's a slightly change over AOL Instant Messenger. There's also a large amount of very similar software or straight-up slack clones that are not very popular at all.
I would say what makes Slack so popular is how easy it is to set up and get running, both as a service and for every user, combined with the availability of easy integrations/plugins.
I strongly disagree. Slack has nearly the same UX as every chat platform of the past 2-3 decades. It's a slightly change over AOL Instant Messenger. There's also a large amount of very similar software or straight-up slack clones that are not very popular at all.
I would say what makes Slack so popular is how easy it is to set up and get running, both as a service and for every user, combined with the availability of easy integrations/plugins.