Law enforcement can subpoena Google for breadcrumbs, and then go to data brokers for the missing pieces. It's not perfect, but this likely isn't the reason for Jitsi doing this.
The real reason likely falls along the line of the extra requirement driving people away from misusing the service, if they now need a VPN + killswitch and a burner "faang" account to share illegal content. They'll just go to the next common denominator sadly, resulting in truly anonymous services dropping like flies (anonfiles.io being the last example of this)