It’s simply because the tool itself is not enough and it will not lend you magical qualities, neither the talent to shoot the proper quality photo. As all tools, a superb quality camera is only a useful tool, once you have mastered all the proper skills to be able to use it properly.
This is exactly why everyone is encouraged not to be all too keen to buy a camera which is super expensive neither a camera that’s very complex.
Stick with a camera which is good quality, cost effective and can make good photos in any and every condition. Most of Nikon, Canon and even Olympus cameras are up for the challenge.
Do not get all too obsessed with camera quality all too soon. Talent matters so much more and without the talent there won’t be improvement whatsoever.