I think that "ground" was added in the 2nd Edition of the Red Barricade rules. The Q&A (again I think) is from the 1st Edition era.
I notice that "ground" is not present in the VotG rules, but then those are based on the 1st Edition of the Red Barricades rules.
Designers of new CGs seems to base their rules upon the obsolete 1st edition Red Barricades rules, silly old activate-reserve-rule will place and move a FighterBomber/DiveBomber through 5 hexes that will cover a total of 19 hexes and any enemy reserves in those 19 hexes will be released.
We played/ or did not play, with that old rule in the early beginning but stopped with it rather early on in mid-game, when discovering the silly effects or perhaps we never played with it since we thought activation of reserves could not be made by planes "flying over".
It is considered Gamey, especially when an mistaken attack is made since the opponent will choose which attack-of-approach-in-five-hexes the stupid plane will fly over.
If a designer think that this gamey aspect is great fun, good and all power to his gaming sessions (
excellent play). Thankfully the rule in Red Barricades improved on this aspect and banned it while other new CG keept that old rule that was in error from the very start.