> This may result in a situation that strongly favors the defender. If it takes ten drones to shoot down a fighter but they're only 1% the cost, countries that otherwise can't project air power internationally may become capable of defending themselves at home.

This exists already. Those "drones" are more commonly called surface-to-air missiles.

The limited factor is targeting: as has been well publicized, modern aircraft have been engineered with stealth in mind, which means they need to be quite close to radars before they can be detected.

The solution, which was discovered in Yugoslavia, is to use low frequency radar to detect the stealth aircraft, and wait until they get close enough (defense in depth is necessary here!) before turning on your target grade radar at the last moment.

As you might imagine, this is a difficult and dangerous process, and so has only been successfully accomplished once.