Earlier quoted context omitted.
I don't think people want IRC for the lack of functionality. I think they miss IRC because they see in Slack a real threat to decentralization, privacy and openness. I don't use IRC. But I'd never use Slack either in a project I maintain/lead. We need a better alternative.
Also, slack is like a dumbed down version of IRC. As an example, on IRC you could run an auction or a 10000 person university lecture because there is a +m channel mode (moderation). +m quiets all users in the channel and only allows you to speak if you receive the channel-user mode +v (voice) or have +o (operator status). Some ircds also have a +h etc. You can setup bots like “RaiseYourHand” for people who want to a…
Just imagine how much better Discord, Slack, et al. could be if you could host your own instances with your own rules and with your own extensions.