The problem with cropping isn’t with the cropping itself. As long as you don’t resample the images, cropping is fine. Say you crop one image and it ends up 3,865 pixels tall and another one cropped is 4327 pixels tall….. if you leave them that exact size then everything will be fine. However, if you force them to the same size after cropping, then it will mess things up. The image that was 4327 pixels would need to downsize by a larger % than the image that was 3,865 pixels in order to make them both 3,000 pixels. So yuo are putting in artificial scaling differences.
What most people do when the crop is have lightroom export to a fixed size. So that is where the scaling differences get put in.
Hope that makes sense… not sure if I explained it well or not.