Your assessment is essentially correct and typically underestimated. Rare transmission errors are not "no error" and are comparable to amp clipping: most people hear them, but ignore them. In pictures, that mean a small square could retain the previous' refresh image while the rest of the screen get the new image. It is not a YUK WHAT A MISTAKE problem, but it is a diminishing image.
They IS a difference between crappy cables and adequate cables. Not believing in 150$ cables does not mean 30$ cables are as crap! But it does mean that 1$ cables may actualy induce subtle failures that are harder to miss.
