Because unlike when you’re up against ground vehicles, there’s no positioning on the planet that can prevent you being attacked by multiple vehicles at once.
Besides, many ground vehicles are entirely able to survive fire from multiple enemies at once, so long as they position appropriately and don’t allow themselves to be flanked. How do SPAA pull that off against CAS, I wonder?
As exemplified by your stirling results in the M16, M163 and Sgt York? You tout yourself as an SPAA expert, but in every SPAA incapable of tank hunting, where you cannot use that to explain away the low KD against air, you still have a low KD against air.
Generally, the plane has already seen the SPAA’s position, either by it baiting the SPAA to shoot at it early, or it shooting at something else. Or having a squadmate ping the location. I have a buddy who does these sorts of strikes in a SAAB-105 at 10.7 using this tactic. It’s very consistent, especially with rockets to further reduce the target’s reaction time.
While Thunderskill is not an all inclusive dataset, and it does have biases, those biases are completely irrelevant it regards to your contention, that there aren’t enough CAS planes to shoot down at 9.0 for it to be useful.
No amount of bias in the Thunderskill population is going to magically spawn planes that don’t otherwise exist just for them to shoot down.
I’m going to keep asking the question you’re dodging until you answer it. How do Thunderskill players manage to generate planes to shoot down that you assert aren’t real?
I literally played one match at 8.7, got an uptier to 9.0, played it, and stopped playing at that tier. The rest of my games that day were at 6.7 or 4.3.
But congrats on almost understanding my point that personal anecdotes are next to useless when it comes to establishing trends.