I don't understand why this is hard to figure out. Perhaps you are like lawyers and the point is to make an argument even if you know your client is guilty.
Speed, firepower, climb, turn, roll, visibility, acceleration, stall behavior, and dive performance are the big factors in what makes a plane easy to get kills in. Other factors like toughness, fuel capacity, etc matter as well but to a lesser degree.
The better the plane is at these attributes the bigger the 'window of opportunity' is to get a kill. A pilot creates his window, while his opponent tries to shrink it. In creating opportunity to get a kill, a pilot must optimize his movements vs his opponent's movements. As the capability of the opponents aircraft inceases in any given attribute, that optimization gets harder and harder. As it also gets harder with the reduction in the attributes of his aircraft.
The ability to optimize is the definition of pilot skill.
The planes with big attribute envelopes, like hispano armed Spits, N1k2s, Ki-84s require less optimization to get or keep a bandit in the 'Kill window'. Hence Easy Mode
Saying the pilot makes his own easy mode, and the plane is not a factor is kind of silly Way'.