For #1 I think it's simply a bandwidth and latency issue. Say you are using webrtc to do a video call. Now imagine the same thing but with 10000 peers sharing

For #1 I think it's simply a bandwidth and latency issue. Say you are using webrtc to do a video call. Now imagine the same thing but with 10000 peers sharing their video. That means each participant has to upload their feed 9999 time while at the same time download 9999 videos from random peers around the Internet, each one with their own bandwidth and latency restrictions and each one doing the same thing as you (uploading and downloading to/from 9999 peers)