IRC still exists but the age or IRC is long over. Sure, people still use it, but some people still use myspace. IRC is lacking most of the features that the average person considers the bare minimum level of features.

Being able to see messages while your computer was turned off is bare minimum. Being able to use your phone to connect and receive push notifications is bare minimum. Being able to share a photo is bare minimum. Having a profile picture is bare minimum.

Some of these features can be sort of had with client extensions or middle steps like irc bouncers but the average user does not care for this. It should just work and every other platform just works.

The average user also doesn't care if the proprietary messaging platform of the day dies and is replaced with a new one because its easy to sign up again on the next platform