Technically an SFU doesn't need it. But clients connecting to the SFU will probably need it. Also having a TURN server allows for very restricted corporate sce

Technically an SFU doesn't need it. But clients connecting to the SFU will probably need it. Also having a TURN server allows for very restricted corporate scenarios, such as everybody connecting through a single, well known port (as Sean's S.O. reply mentions in the sibling comment). For example in OpenVidu (not trying to plug it here so won't put a link) a Coturn server is deployed, and TURN credentials are automatically shared with all clients (web browsers, mobile phones) so they can access the SFU through the Coturn instance, if needed. People are using this on very restricted networking setups for allowing connections between differently segmented networks, some of them not even connected to the internet.