Sure, but it helps and it is cheap. I also don't use a common subnet and enjoy uMatrix. Obscurity is a viable strategy as part of a layered defence. ;)
My main problem is that blocking WebRTC blocks some very interesting methods to "re-decentralize" the web, which are only viable if most people don't have it disabled.
This is a classic conflict that I’ve observed a lot. Similarly, widespread SSL pinning and app sandboxing makes it difficult to reverse engineer opaque outgoing traffic. It might be more secure, but you also cannot easily inspect what data a sandboxed, cert-pinning service is sending to the outside world.
I think it’s probably something like “security, privacy, anonymity... pick two.”
