With very high PPI displays the gamma corrected interpolation scaling is far better than nearest neighbor scaling.

The idea is to make the pixels so small that your eyes aren’t resolving individual pixels anyway. Interpolation appears correct to your eyes because you’re viewing it through a low-pass filter (the physical limit of your eyes) anyway.

Reverting to nearest neighbor at high PPI would introduce new artifacts because the aliasing effects would create unpleasant and unnatural frequencies in the image.

Most modern GPU drivers (nVidia in particular) will do fixed multiple scaling if that’s what you want. Nearest neighbor is not good though.