He's probably right they are features, features most people prefer over IRCs barebones experience. Not being able to catch up on what was said while you're offline is another one of IRCs features, sadly even less people seem to prefer that.
I'm someone who likes the idea of IRC being impermanent, available only if I was online at the time.
However, I also want people to be able to @mention me so that I can see it later, even if I was offline, overriding the default. AND, when that happens, I also want to be able to read the context before the message and probably some conversation after. In other words, I want "@smichel17 ^" to be a thing.
I don't see any way to combine those features. I can approximate this experience in Discord and its ilk by having all history about l available; muting conversations, except for notifications; and relying on willpower not to read the backlog unless I was mentioned. So that's what I do. Maybe the closest thing would be Snapchat, where messages can be "saved" by any of the participants so the whole group can read them later.
There's no way to approximate this experience in IRC. So although I still use IRC, it's mostly over a matrix bridge; matrix becomes my bouncer.
Yes, there is.
<bmn__> !tell smichel17 crowdmatch me, see HN frontpage
<reminder`bot> 1 message stored. will deliver when smichel17 rejoins or unaways.
⋮
* smichel17 is no longer marked as being away, gone 04:30:55
<reminder`bot> smichel17, bmn__ wants you to know: "crowdmatch me, see HN frontpage" (2021-12-28 13:12)> In other words, I want "@smichel17 ^" to be a thing.
What was being described was more like saving a highlight; with much less friction. On Discord, I can @someone even if they're a nickname-only user with no account.
I've been doing this with IRC for about 3-4 years now, and it means that I'm "always online" as far as IRC is concerned (except for server maintainance stuff). To a reasonably approximation, I never miss anything.
From this perspective, the "always online" approach just makes IRC like Discord et al, where you receive everything and have to choose what to read when you get back.
Snapchat is the closest, with its "messages disappear after 24h by default, but can be saved by members of the group".
With Quassel at least, private messages show up elsewhere, tagged messages will generally be color-coded for easy identification. I suppose that people who participate in busier messaging systems than #ardour on libera.chat may need the sort of thing you're referring to, but it is so foreign to me that it's beyond my imagination.