> How do you do it in IRC?
The question was how to see that threads are getting messages, and following them. IRC doesn't have threads, so doesn't have this problem.
On a higher level, how do I follow different conversations happening on IRC at the same time? I wouldn't say it's ever been a problem, in the decades that I've used IRC.
Hell, I use some IRC bridges that just flatten all the threads into one timeline, and that works much better too. Yes, in theory someone could just reply "yes" 10h after the previous message on a thread, and you have no way of knowing "yes to what"? But in practice that basically never happens.
Now, if the sender of that message had been on IRC, they would have instead said "yes I'll come to the dinner". Which would have been REALLY helpful on Chat too, because people may get popup notifications (phone or desktop) that just say "yes", and now they have to find (much harder than it should be) and open the thread to even know what the question/topic was.
And yes, people will probably also adjust their timelines a bit. Like if there's a major outage, maybe in modern Chat people start a thread to discuss a weekend trip (though do they? I'd expect them to start a completely separate group chat), whereas on IRC maybe they would go "you know what, this discussion can wait until after the outage". But people do that with modern Chat too. It's not just that the Chat is busy, the people are busy too, so you wait.
Still, there's no problem having a couple of conversations.
If you feel like I'm not answering your question it's probably because you seem to be saying "how do you solve this problem in IRC?", and I honestly don't understand what the problem is.
I have a WAY harder problem keeping up with newer chat. Right now on my work social chat my full desktop monitor has enough vertical space to show a whole 5 messages. My IRC on the side on a smaller monitor is showing 28 messages at once.
Now, because the Chat is Google Chat, those 5 are all I'll ever see, because if I try scrolling up, the page starts dynamically populating messages, causing a bunch of scrolling, flipping pages up and/or down losing my place, so I just give up and chase the ephemeral "Jump to bottom" button before it decides to disappear.
I'm pretty sure Google Chat is the worst of all options in terms of UX, so I'm not saying Slack is as bad.
> You can do that on Discord (it keeps track of read/unread messages)
In my experience the number of threads people create will greatly exceed the ability of even a "supertasker" to keep click-click-clicking to follow. Basically if this isn't the thread you have open, you're not on it.
> Obviously this is unreasonable if the Discord server/IRC channel is high-traffic.
If an IRC channel is too high traffic, it tends to topic split into another channel. And IRC clients can certainly keep track of what you last saw.
> pinned messages
Channel topic serves that purpose, I think. Or maybe not for the way you use pinned messages?
I think the only functionality I'm missing in IRC is the ability to attach images and receive them inline if needed. Gotta have the memes. And some clients (e.g. irccloud) do support that.