I'm explaining to the parent why "I don't understand this world" isn't a reasonable response. If you've used Slack and IRC for 5 minutes, you should know why most users prefer Slack, even if you prefer IRC.
I don't use Slack regularly, but I have tried it, and it is instantly obvious what the difference is. If you don't see it, then you probably have never designed software for end users. (FWIW, I also agree that Slack is bloated and that's one of the reasons I don't use it.)
As far as contributing to free software and open protocols, I'm working on fixing Unix shell. It would be great if IRC developers would take some inspiration from Slack and other proprietary services and fold them into IRC. Although, as mentioned in this thread, some of that may be very difficult or impossible without a commonly accepted client.
And I understand it's not a one person job. It probably requires a more coordinated effort. Decentralization has drawbacks as well as benefits.
What is not OK is pretending that problems with IRC don't exist. If you have that view, and spread it, then you guarantee that open protocols won't win.
I prefer open protocols, and I lament what has happened to Usenet and e-mail (trying to set up a mailing list for my open source project has been frustrating; spam causes problems for mailman-type lists). But honestly the proprietary services have innovated. They're not better in all respects, but they are better in some.
Open source doesn't mean being ignorant of users and dismissive of their complaints.
(FWIW I didn't know about IRCCloud. It looks interesting and I may check it out.)