Facebook Live is hardly just an 'API', it's the right to use their paid network to stream video to thousands of people in the world simultaneously. Live stream

Facebook Live is hardly just an 'API', it's the right to use their paid network to stream video to thousands of people in the world simultaneously. Live streaming gigabytes per second is not cheap, and its not surprising they'd only want to do it from their own app where they can at least show you their ads to try and recoup some of the cost.