I think that the reason is the same for “why is XMPP mentioned more than IRC?”. IRC has more clients, it’s less resources hungry and simpler than XMPP.
I think that the reason is because it is old-fashione, and it’s clients feel outdated and (native) “lacking features” compared to more popular clients like Discord, WhatsApp, Messenger, Telegram or Signal. 🤷♂️
I can imagine my cousins using any of the clients I mentioned before, but not IRC, XMPP, or any protocol from my era. Life and traditions, isn’t it?