Originally posted by hadi for me, its not gear related. its portrait related. whenever taking pics of someone, if on a certain frame the picture is perfect, with great lighting, sharp, bokeh etc, composition everything is perfect; and you as a photographer think its a perfect subject. and then someone comes along saying 'you cut off their feet. it implies they dont have feet' or 'you cut off their hand/finger/elbow/hair/etc, it means they dont have that part'.....
Yes, this is the world of aesthetics, Hadi.
The line of argument is, you've spent so much time getting the light, sharpness, bokeh right as you mention, that you don't want someone to look at your photo and instead be transfixed that the subject's hand or foot is cut off, not noticing everything else you've achieved.
To stop that being a distraction, the conventional wisdom is that cropping shouldn't occur at a joint in the human body.
Sometimes this can happen because the frame contains another person or object that competes with the subject, so in post processing there's an attempt to solve that with the cropping tool. Equally ugly is an attempt to get rid of the object by cropping to an aspect ratio other than 3:2 - it can be pretty obvious that the photographer is trying to cover up a mistake.
The real answer lies in the shooting, not the postprocessing. We all really need to peer into the four corners of the viewfinder to make sure the composition is clean before pressing the shutter button, rather than trying to fix mistakes afterwards.