In some graphics programs, as of the last time I used them, which has been a few years now, to resize proportionally with the mouse requires pressing a modifier key in addition to grabbing a handle and dragging. Graphics #UI
designers could reduce size distortion by making the easiest resizing method be proportional, and making distorting things require the additional effort. Also, graphics elements could have a property of "Allow distortion or not", so you could assign things like picture of people or things that are supposed to be perfectly circular or perfectly square, etc., a value of "No size distortion allowed".
Another things designers could do to reduce this problem is have an "Original or designated as correct aspect ratio" for graphics elements so if you find something distorted, as when you see now that you accidentally distorted something, you can easily fix it perfectly with no trouble and no guessing.
I used a program that took the correct, let's make it easy to keep from distorting shapes, and easy to fix size distortion errors, and it was much nicer than having to constantly remember to press Control or Shift or Alt like one has to do in many programs.