I disagree that it's merely a UX deficiency, but I agree that it's not a protocol deficiency. Yes, indeed you could just use an IRC bouncer: the problem is that many users don't have easy access to such a bouncer. What IRC "needs" is a network of open bouncers that users can subscribe to.

So IRCCloud?

I couldn’t imagine joining a workplace only to be told that I had to maintain a service to participate in essential communication channels.

Exchange servers anyone?

If my workplace made every employee run an Exchange server rather than IT running one for everyone, I'd leave

So you're saying an IRC daemon for corporate use needs a competent administrator, which is true of most daemons in business situations.

Could it just be a donkey image that spins up with the convenient bits in place?

I have a hard time imagining irc heads don’t have a solution dockerized

I had a bouncer (with push notifications!), but I was in the minority.