Are there any benefits of hosting your own XMPP server?

I host my own. I'd say my contacts are split between XMPP and Matrix with many people having both. A lot of business use self hosted XMPP servers too. For example, Cisco communications solutions are based on XMPP.

The issue with free public servers is that you have no accountability. If they go away, or are left unmaintained, there's nothing you can do about it.

My two cents, host at home, or at an infrastructure provider you pay for service.