Many of the paint points are solved when using alternative clients. Alternative clients will allow you to, for example:
* Use Slack on an ancient computer
* Use TTS systems
* Not use threads (you can just dump everything in the channel)
* Not have link previews
* Use keyboard only
* Get a less distracting experience
I'm also an IRC user and I like it but I just wanted to point out the post isn't fair with Slack if only one client is evaluated.
Edit: list formatting