It's also WebRTC based, which takes the load off the Jitsi server considerably. Popular alternatives like Zoom requires rerouting traffic through their servers AFAIK.
This is only for users that have public facing IPs. Most users are behind NAT, so WebRTC will still require relays (TURN servers). I'd assume majority of users are behind NAT.
My brother told me today was looking for a way to move his classes online, to keep his income while coronavirus is hurting his art centre. I found jitsi.