Nobody is claiming that the K-4 is as easy as the Spit XVI. What we are pointing out is that, contrary to how the K-4 fans talk about it, the K-4 is actually well on the easier side of the bell curve. With just an idea of how it is supposed to be used a player becomes nigh untouchable to a whole range of aircraft and while he may have trouble getting kills at first, he won't be dying as much either. Not dying is key to getting better because the time spent getting to a fight doesn't help build skills at all and if you die in the first 20 seconds after engaging, well, there is a lot of not building skills going on. Contrast that to, say, a P-40E or Ki-61. Those fighters can be quite successful, but a new player isn't really going to build the required skills in them unless he is very dedicated because they don't offer much in the way of survival tools.
If a P-40C is a 1 on the difficulty scale and a Spitfire Mk XVI is an 10, then the Bf109K-4 is probably a 7 or 8. Yes, harder than the Spitfire, but easier than average by a significant margin.