A button-pushing mouse (far lower than "newbies") can kill millions if his weapon is a nuke with a big red button.
By that I mean it doesn't matter if they're newbs or not, the spitfire is by far the easiest plane to get kills in, and in fact allows newbs to get kills they otherwise would not "earn" (I use the term loosely).
More pilots learn bad habits in spits than any others. Spits can do moves other planes can't dream of in this game. Also, spits shoe-horn the lesser pilots into flying nothing BUT spits, since (as you say) they're newbs and only some of them want to actually learn anything. So they keep flying the one plane they can kill with, or they get no gratification (read: no kills makes Jack a dull boy).
P.S. I think they're nice in the real world. I also think Aces High has it wrong (as with a number of planes) and the spit has no vices whatsoever in-game. I count it with the P-51s, P-39s F4us, Ki-84s, Ki-61s, that all have major issues (IMO) with their current flight model.