Comment by pixelesque

It is.

Some modern films are still filmed with anamorphic lenses because the director / DP like that, and so we in the VFX industry have to deal with plate footage that way, and so have to deal with non-square pixels in the software handling the images (to de-squash the image, even though the digital camera sensor pixels that recorded the image from the lens were square) in order to display correctly (i.e. so that round circular things still look round, and are not squashed).

Even to the degree that full CG element renders (i.e. rendered to EXR with a pathtracing renderer) should really use anisotropic pixel filter widths to look correct.