I don't get this and I don't think it's true.
If you make any tiny movement on the shot, it's the size of the pixels rather than the number of pixels that determines whether or not the camera movement affects the image.
However you never hear people say that you need to have top quality technique and skills when using an entry-level DSLR. But the pixel pitch on a D3500 is only 3.89µm, compared to 4.34µm for the D850.
And you never hear people saying that you need to have top quality technique and skills if you're thinking of downsizing to a smaller camera system, but the pixel pitch on a 26 megapixel Fuji (eg X-T30 or Fuji X-T3) or a 16 megapixel Olympus (eg E-M10 III, E-M5 II) is only 3.74µm.
Now this I do understand. For any given composition, more pixels = finer detail = more vulnerable to subject movement. But not necessarily more vulnerable to camera movement.