In the advanced settings, users can select STUN/TURN servers and specify whether only TURN servers should be used.
Actual behavior
Users cannot select STUN/TURN servers and specify whether only TURN servers should be used.
Explanation
I think it would make sense for technically savvy users to select STUN/TURN servers. Furthermore, the option to use only TURN servers would allow users to hide their IP address and thus better protect their privacy.