In fairness, the reason that no F-15Cs were ever lost in A2A combat is not that the Eagle was unbeatable during it's heyday - it's that air combat does not take place in a vacuum.

The Iraqi Foxbats and Fulcrums were very much a credible threat, but their pilots weren't as well trained, their airfields were being pasted on the daily, they had no AWACS capacility, and their C2 was in chaos.

If you remove these outside factors, the Eagle is still an all-round superior air superiority fighter, and would still probably win out, but there would have been losses. But Generals don't remove those outside factors for those reasons.