It's rock solid in what it does, I have zero doubt about that or your 15 year claim. But even if the protocol works, if the user base isn't being added to it will die eventually.
If you are really referring to phone notifications, well, you can use an IRC client on your phone, then you would get notifications on your phone. I use irssi even on my Android phone.
Let us not forget that there is the other side of the story: many people report that they have been enjoying life more without those phone notifications.
I love IRC. I have been using IRC ever since I was 11. It made me a more technical person. I find that IRC is not that easily accessible to the majority, which is a good thing, because of this, the conversations tend to be of higher quality, and technical in most channels. I would also like to add that IRC is the reason I understand English, and a zillion other things. :)
With phone notifications, you not only need to work for things that happened while not connected, it's bad form to require a permanent connection on android and you can't do it at all on an iphone.
I don't miss anything.
I have that with a bouncer (znc) and a plugin. I've not used it, but it is my understanding that IRCCloud does this too. Problem is that there aren't many easily usable options for this apart from IRCCloud and even IRCCloud itself isn't all that well marketed.
Always seemed kind of weird how while IRC is full with FOSS people who are willing to use their time on various projects they're not getting paid for, most of whom also seem to worry about IRC dying out, nobody is really doing anything about it. A lot of the conveniences we miss could mostly be solved by making modern clients that are actually good.
It works very well now, and the Android client is pretty great too, but there are still some gaps. Mainly, the surrounding ecosystem is quite sparse, e.g.: - There is basically only a single web client for it (node-based, which is a con from my perspective) - There are only a handful of semi-functional log searching/browsing utilities around
I think it also dampens the same for traditional paid software in a lot of areas, incidentally.
Which is, sadly, a lost cause. We had a simple, reliable, open, decentralized base that simply did not adopt to the needs of a changing userbase of the internet enough. Non-technical users have expectations that are incompatible with the text only format and they prefer platforms that feel more like their other social media tools. Technical users don't fix that and get riled up about nonsense instead, like non-TLS connections and other points that were addressed a decade ago, alongside people that just prefer a more decentralized system.
It feels like xkcd #927 is also relevant [0]. The open source world in chat/social platforms often looks like Googlers looking for a promotion instead of addressing real needs and most efforts seem to be drowning in irrelevance. Even technically sensible projects like Matrix, who's going to use that? Not the instagram crowd that's for sure, heck, many technically inclined people cannot be bothered with IRC when the alternative is convenient. I'd be really surprised if we see a widely adopted open messenger in 10 years, it's more likely that people just settle on a new random walled garden every 3-5 years.
I noticed myself using IRC less for this reason. I'd always run weechat on servers so I had the history but never thought to look for notifications these days.
I signed up for IRCCloud and it's been nothing but excellent so far. I can even connect weechat to it like a BNC.