That's false. Go look at the difference in flying ww1 planes vs ww2 planes vs early jets. Speed and maneuvering and E retention have a major impact in the fight SA zone of combat. I can see you've never played FSO or axis v allied scenarios very much.
Thats not "false." It's called relative comparison.
If flying a WWI plane is difficult, then by extension, it's also difficult to fly a WWI plane against another WWI plane. Ergo, when everyone is in WWI planes, there is no difference in variables aside from pilot skill.
If SA is reduced in WWI planes, then all pilots have reduced SA. Since you have clearly stated this isn't due to pilot skill but rather the "reduced E" and other items, then it logically follows that all pilots SA is reduced accordingly. Therefore, the only differing variable is pilot skill.
Ergo, in every situation, it follows that when the planes are the same, the only difference is pilot skill. When all planes are the same, then plane type doesn't matter; only the pilot's skill matters.
You really need to learn basic foundations of debate. This is basic logic.