Have you actually tried the modern clients like Conversations/Dino? I've been running a private XMPP server for friends for the past couple of years and the only way to describe it is rock-solid.
Even Matrix with Element (which used to have quite a few issues with slowness and encryption), works way better these days
Not to mention any widely used centralized messenger...
Element desktop is... slow and terrible in comparison with all of its confusing options, and regularly kicks just a single person off the server for no apparent reason when their session becomes corrupted. I really want to use fractal but it doesn't do E2EE.
Synapse was a horrible resource hog, but conduit actually seems pretty good. Still prefer ejabberd.