There are many reasons. - Not everyone has such good connectivity. - So you can handle many streams at once, like in a big meeting, without a server mixing th

There are many reasons. - Not everyone has such good connectivity. - So you can handle many streams at once, like in a big meeting, without a server mixing them. - So you can have decent quality video on the same limited connection. - So you can archive large amounts of speech. - To advance the state of the art. - etc.