The USAF, USN, and USMC sure was in a big hurry to replace the F-4 after the Vietnam War. It remained in service, but just because we had a lot of them. It suffered from a lot of the same flaws the F-35 does. It overly relied on electronics rather than aerodynamics. It was not maneuverable compared to the aircraft it faced in combat. The Navy developed the Fighter Weapons School to try to give its pilots a advantage over the simple yet maneuverable Migs they faced. Just as an example of how ill suited the F-4 was for dogfighting, the Navy FWS actually taught a maneuver to depart the F-4 while in a 1-circle fight. While departed, the aircraft could be induced to yaw very quickly. This enabled the pilot to slew his nose ahead of the other aircraft. Should you really have to depart an aircraft in a dogfight? Desperate times called for desperate measures. The F-4 was a big reason the USAF developed Red Flag also. The F-4 was really a mediocre aircraft. Extensive pilot training is about the only thing that made up for its deficiencies. Like I said, the U.S. was real quick to develop replacements for the F-4 after seeing its deficiencies in Vietnam.