It was replaced by group chats, Discord servers, Telegram groups etc.

it is not dead, just that the masses have their shiny full of gifs and spread in 50 channels per topic alternatives now.

Isn't discord this generation's IRC?

Not really, the company can unilaterally ban someone or a server. With IRC you can start a private server and you are not at the mercy of anybody else. And you are not nagged all the time to guilt your users into boosting the server so they can use more features. Your users don't have to pay if they want to have different profiles on different servers. Your users can use any interface they want to access the service...

So you are right in a sense that discord replace IRC as a means of communication for the majority, but in term of freedom it is a regression. If IRC had supported offline history keeping things could have been different, but for the people I know it was a major blocker for adoption. They didn't want to have to setup a server to bounce from or keep something running all the time.

discord is this generation's yahoo groups.

Kind of. IRC had a culture of its own.

Also yungins might be surprised to learn that we had a distributed, open source communication network, where basically any dipshit with a static IP and a Pentium could start an IRC server and maybe get added to the network if they were reliable enough (I was one such dipshit).

irc isn't dead, come join us on Libera! (and there's tons of other networks too, i just feel disingenuous inviting you to ones im not on)

What did you check? I'm in some channels like #postgresql or the channel of a hackerspace I'm part of and it's always active.