but God is it painful to self host an xmpp server

You are in for a world of pain regarding Matrix if you think xmpp is painful to host. Compared to hosting a Matrix server, XMPP is very pain-free to host. Sure, it takes a slight bit of effort to understand that there are other protocols than HTTP, but beyond that that initial learning curve, XMPP servers are extremely hassle free.

And you must have used extremely outdated clients. All the modern ones (which there are plenty) support replies and reactions etc. ootb. Let me guess, you only tried Pidgin? That client hasn’t been updated for xmpp in 15 years or so, and is by far the worst.