I guessing it's because Webrtc is near real-time whereas transcoding to HLS would add latency. However the advantage of HLS is that you can offload the serving

I guessing it's because Webrtc is near real-time whereas transcoding to HLS would add latency. However the advantage of HLS is that you can offload the serving of the content to a CDN or a Http server and scale horizontally. Whereas serving more webrtc clients would require fatter/bigger webrtc server. Please note I am only basing my opinion base on what I have read on HN.