Well, that is a protocol comparison. A client comparison would be much closer to the real world user experience. Don't get me wrong, I am a huge fan (and daily user) of XMPP, but the best protocol will not be of any use if the clients are too complicated or buggy to use.
So yes, XMPP supports audio and video calls but finding two different clients which work on the first try together can be a challenge. Sometimes I wish there would be some compatibility XEP which defines a common set of supported XEPs including a test suite to run it against.
We have the XMPP Compliance Suites 2018[0] providing an overview of protocol-level specifications that a modern client or server should implement, and there was recently a nice article[1] for some example use cases.
What is still missing is everything above the wire protocol level. The XSF, being the XMPP Standards Foundation, is guarding the protocols, and things like UX and client interoperability are considered as off-scope. However, there are people interested in these topics as well looking for fresh collaborators.
That looks pretty cool. Maybe I should ask SamWhited why they didn't include OMEMO, Audio and Video Calls as features as he is writing in this thread too :D
So yes, XMPP supports audio and video calls but finding two different clients which work on the first try together can be a challenge. Sometimes I wish there would be some compatibility XEP which defines a common set of supported XEPs including a test suite to run it against.