As a preface, I'm not telling you not to use IRC. If it works for you, if you like to use it and deal with its quirks and anachronisms, more power to you. There are loads of great communities out there on various servers.
Having said that...
I couldn't in good conscience recommend IRC to a hypothetical someone who's never used a chat program, under almost any circumstance. The feature set is truly beyond meagre by modern standard, with some, though not all of these shortcomings being resolved by standing up, and administering, a bouncer, and (if you're using something like irssi) a stew of Perl incantations. Which, again — I'm not bashing, necessarily, but Perl just isn't a language most people are learning these days, for a number of reasons.
Following up, though:
- Admining a bouncer, while not a full-time job in the long run, is something you need to keep on top of, from keeping the host up (both in terms of potentially paying bills if you're using commercial hosting and in terms of making sure resource usage is fine, nothing's crashing, and security updates). It's also nontrivial in the strict sense: I couldn't teach my parents to do this.
- `tmux` or `screen` are _easier_ options, but man, it always feels dodgy to use them like this. I ran Python servers like this when I was an intern because I hadn't figured out how to create an init script and before Docker was the staple that it is now.
- Other commenters have pointed out that Discord, Slack, etc., have occasional sync issues between devices -- but *at least they support multiple devices.*
- Search is functionally non-existent without a bouncer
- Once again: this is a feature that's not prefect on other platforms, but at least it's *there.*
I'm not making the argument that Discord/Slack/whatever are universally better than IRC in every way. I'm trying to argue that their usability is top-tier compared to IRC, for most people. I also won't say that Discord "killed" IRC. IRC is an older-generation chat protocol/UX, and by that logic it's gonna keep getting killed with every new generation of chat client. First, it got killed by Teamspeak, then Slack, and now Discord, each using their feature sets and UXes to chip away at what's left of the IRC user base.
This isn't even touching on the other features offered by these chat platforms that IRC just doesn't really touch -- mainly, reasonably reliable audio/video calls and screen sharing. And I gotta say, dealing with self-hosted live video streaming is surprisingly hard to get right for calls of more than 2-3 people, generally speaking.
There's some argument to be made about data ownership, but honestly, the more time goes on the less I believe most people care about that very much for casual chats. If you're worried about the government or (much more likely,) advertisers coming after your private chats, IRC is absolutely not an inherent solution to this, and is by default probably about as bad as any centralized platform in this regard.
Use whatever you want and what works for you. I genuinely don't care. But don't deal in absolutes like this; you'd have to be really full of yourself, or totally out of touch with reality and how users interact with software to make a claim like this article's title. Discord and Slack aren't perfect, and certainly, IRC power users who've been on that platform for years or decades may find it falls short in some ways, but for the average person, they're both likely better alternatives.
It's also kinda weird to fanboy over this kind of thing, which is the impression I always get from these posts. "I use X because the communities/friend groups/features/tools I like or am part of are there" is an extremely valid subjective argument for preferring a platform. "I dislike Y because it has A, B, and C issues which break the user experience for me" is just as valid and more objective. "Everything that's not Z is bad because of $PERSONAL_MORAL_FRAMEWORK reasons, and if you wanna put the work into it, Z can be usable actually."