A filter is a weighted average and a box filter treats all pixels the same. Upscaling with a box filter barely makes sense because it will either end up samplin

A filter is a weighted average and a box filter treats all pixels the same. Upscaling with a box filter barely makes sense because it will either end up sampling a single pixel (impulse filter) or blurring the image even more than normal upscaling. "Bilinear downscaling" also doesn't make sense because scaling an image down means doing a weighted average of the multiple pixels going into a single pixel. Pixels being weighted linearly based on distance would be a triangle filter. Aliasing is therefore more limited and controlled. Aliasing doesn't need to happen at all with a reasonable filter width. If someone is interpolating between four pixels, that's a triangle filter with four samples.