[lolinder]

This is an overly reductive summary that isn't backed by any of the stats--the number of IRC users has declined well below the number of professional developers. Dozens to hundreds of open source projects were already on Slack/Discord before the explosion of Freenode, dozens more switched when that happened. It's not as simple as "professionals use IRC, gamers use discord".

You could definitely argue that IRC appeals more to the kind of developer who spends their entire day in the terminal and Vim--but that's not the only kind of developer out there! Just like many developers prefer IntelliJ to Vim, many prefer Discord to IRC. Discord and Slack both offer real improvements for some workflows, and some people value those improvements.

As an example, persistent chat is hugely valuable in a help community--I often find I don't need to ask a question at all because I can just search in the history to find what I'm looking for. Even something as seemingly frivolous as reactions is quite useful--one person can answer a question and get a chorus of 'amens' without actually having a bunch of "what he said"s in the chat.