Having worked in high security environments, I could see a possible legitimate reason for original request, where the video compositing features to record is desired, BUT streaming is a no-no. A firewall could easily block outbound traffic on certain ports, or to certain destinations. But in today's world, having some connectivity is often still required. A defense in depth approach would block known destinations and ports, or better yet only allow specifically designated destinations. But someone could put up a listening server anywhere or pretty much any port, so.... I get why someone would ask. But, that doesn't mean the OBS Studio developers should spend any time on this. Someone could review the source code and see if there is a specific DLL or something that could be disabled/removed. Or use local firewall to block ANY outbound traffic from OBS Studio (as in a high security environments, users should NOT have local admin).
so lots of ways to secure a system