OpenGL isn't really any different than Direct3D/Vulkan/Metal from the OS perspective. Shoot until recent times it was the only option on some platforms and if you wanted to use the GPU it was the only way on them.
QUIC uses UDP but not in a "it's relying on UDP" way as much as "layering UDP allowed it to go through middleware boxes" way. The developers of QUIC would have liked QUIC to not depend on UDP, and the protocol works fine that way, but then it wouldn't have went through home routers or corporate firewalls very well. Regardless a lot which used to be done in the OS TCP stack is now handled by the browser application. This is similar to how some other apps have used UDP but that doesn't take away from that fact.
I see. You're saying if they could build OS functions into the browser and not break compatibility with the outside world they would have done that, which means that they're vested in the idea that the browser is the new OS, or can minimize the OS to just the extremely basic no-value-add utilitarian functions. That makes sense why people are concerned or baffled. Thanks.
QUIC uses UDP but not in a "it's relying on UDP" way as much as "layering UDP allowed it to go through middleware boxes" way. The developers of QUIC would have liked QUIC to not depend on UDP, and the protocol works fine that way, but then it wouldn't have went through home routers or corporate firewalls very well. Regardless a lot which used to be done in the OS TCP stack is now handled by the browser application. This is similar to how some other apps have used UDP but that doesn't take away from that fact.