They use nonstandard APIs, and send data over the network in a way incompatible with WebRTC. This post is a bit old at this point but afaik the situation hasn&#x27;t changed: <a href="https:&#x2F;&#x2F;webrtchacks.com&#x2F;hangout-analysis-philipp-hancke&#x2F;" rel="nofollow">https:&#x2F;&#x2F;webrtchacks.com&#x2F;hangout-analysis-philipp-hancke&#x2F;</a>