That tends to happen because military procurement is always a set of compromises, so there lies a tremendous amount of room for basically arguing about how to weigh the different requirements/criteria/mission sets.
Also while the article vindicates Sprey's want of having a lightweight fighter, the reality is that while lightweight fighters did come, they quickly became exactly what Sprey would not have wanted (once the F-16 entered service, it quickly gained BVR capability for example) because the mission that Sprey envisioned (pure within visual range air combat) wasn't nearly as significant in the 90s and onwards.
Also while the article vindicates Sprey's want of having a lightweight fighter, the reality is that while lightweight fighters did come, they quickly became exactly what Sprey would not have wanted (once the F-16 entered service, it quickly gained BVR capability for example) because the mission that Sprey envisioned (pure within visual range air combat) wasn't nearly as significant in the 90s and onwards.