One thing to “learn” is that technologies improve. Big difference between vacuum tube BVR missiles of Vietnam like the early Sparrow (that would malfunction if you sneezed within 10 feet) and a modern solid-state BVR missle.
IFF has also improved.
Technologies that don’t live up to their billing in one conflict can be a different story 40 years later. History is useful, but to proclaim that because of Vietnam, BVR will not work till the end of time is silly.
It's not a technology problem. It's a political problem.
/johnny