"Maoists" are often westerners who have inherited decades of failure to achieve socialist revolutions in their own countries. They are free to spend too much time thinking about what socialism should be and could be in their heads rather than what socialism is. To many of us, socialism is simply the opposite of capitalism rather than its negation, therefore socialism must be the absence of the most hated features of capitalism in our experiences and opinions. China doesn't always live up to these expectations.
If you've never actually lived under socialism, you have no frame of reference for understanding how it's different from capitalism. If you've never seen anything but capitalism, you don't know how to identify its absence. This, more than anything, is what ultras struggle with. I think that's something we can all relate to on some level, even if some have a better handle on it than others.