My issue with this (and WebRTC in general) is that most residential users (at least in the US, probably many other countries) are behind some type of symmetrical NAT or CGNAT, often without the ability to forward ports or have working NAT traversal, which makes WebRTC unusable without a TURN server as it relies on communicating between peers via DTLS over UDP.
The problem with needing a TURN server is that you practically need to host it yourself, because there are no fast and reliable public ones, probably due to abuse. WebTorrent also has the same problem since it also uses WebRTC, and as such, 99% of applications that use either technology simply do not work at all for me or anyone else I've asked to try these services.
Donut still uses WebRTC though, which like I said, I still need TURN for and I can prove it. I still have a really hard time believing that only 20% of "users" (what users where? everyone in the world?) need it, as like I said, almost every residential US user needs it at the least.
The problem with needing a TURN server is that you practically need to host it yourself, because there are no fast and reliable public ones, probably due to abuse. WebTorrent also has the same problem since it also uses WebRTC, and as such, 99% of applications that use either technology simply do not work at all for me or anyone else I've asked to try these services.