I view this passage --
"was a calling which tended to run in families, because it absolutely required a particular Gift"
...as definitive.
Battle Dragon pilots are a small minority of the Arcanian mage gifted population.
A small minority that requires careful training, presuming they have the proper gift in the first instance, to use exacting spellware under the pressure of directing a dragon in combat.
Killing a lot of Battle Dragon pilots is going to do more to hurt Arcanian combat power in the near term than killing dragons.
And note, centuries of combat experience in Arcanian versus Arcanian dragon combat has taught the exactly wrong combat instincts to existing Battle Dragon Pilots than what is needed versus Sharona.
For instance, climbing only works versus the limited engagement range of Arcanian cross bows and "infantry dragons."
You need to be a accelerating, maneuvering, crossing target versus Sharonan anti-aircraft fire. And you have to limit your exposure to automatic weapons.
You don't climb under Sharonan anti-aircraft fire, you dive for speed, jinx, and make yourself a crossing target.
You don't dive on prepared positions with fire breathing Reds, the traditional way Dragons limited their exposure to cross bows and "infantry dragons."
You use blacks at a distance on a lateral/crossing course and spit lightning at Sharonan heavy crew served weapons. Only after you have suppressed the Sharonan heavy crew served weapons with lightning do you go after a position.
And carefully note, very few battle dragon pilots have survived thus far to even begin to develop such tactics.
Frankly, the best bet with battle dragons is as a raiding, as opposed to a main combat, unit.
Battle Dragons are magical battlecruisers, expensive sledgehammers with eggshell protection facing radar directed (Sharonan predictive far-viewers) coast defenses.
Battle Dragons need the equivalent of WW2 "Flak intelligence" on every Sharonan position prior to a battle Dragon attack.
The problem with that thought is that the Sharonans are going to be far better at overhead camouflage than the Arcanians very quickly given the Distance viewer talents. Asking such talent to look down on a position from above and comment on how well aerial camouflage is done will make the delay in recon-griffin imagery a deadly disadvantage.