I don't use Discord's web client and it was ages before I used the mobile one, not that it makes sense to sneer at a native application on mobile but not a native application on desktop. What I have a habit for is using software that works well and has few sharp edges with minimal screwing around. If it comes with a centralized service or total control, that's still miles better than not being able to scroll up to see what people were talking about when you joined. Users do not care about protocols, they care about results. Mastodon proved that you can actually build a usable app on a federated service, so if IRC is the future, I'll consider going back to it once someone goes and actually makes it the future.
The scroll up on IRC problem is typically solved with various "bnc" or "bouncer" mechanisms.
I've also encountered an IRC server that caches and rebroadcasts the last hour of messages.
But yeah with IRC you run into the problem that it wasn't originally designed for that use.
> Mastodon proved that you can actually build a usable app on a federated service
I don't see how anything needs to be "proved." Do we actually need proof that IRC could cache messages and repeat them for joining clients? It just wasn't originally designed that way.
XMPP also has an extension for caching the scroll.