This has been posted before, and the problem with this is allowing multiple people to sing or be on the mic at once requires a lot of bandwidth. Not everyone has super fast internet, so it would slow them down. Plus it would sound off if people lived on the other side of the world because of the time it takes for it to reach from side of the planet to the other. This is called Latency. Unfortunately, for now this is probably not a reality. God Bless you though!
in Christ,
Matt