[gisely]

Chromatic aberration may be a contributing factor, but I am surprised the author didn’t mention that S cones (which we use to perceive blue) are only 2% of the cones in the retina [1]. Additionally S cones are distributed randomly when compared the regular lattice of M and L cones. The distribution of the different cone types alone may be sufficient to explain why our acuity for blues is impoverished relative to reds and greens.

[1] https://en.m.wikipedia.org/wiki/Cone_cell

[arthur2e5]

This lower resolution of blue is pretty well known in recent image compression work (XYB space of JPEG-XL and guetzil), and number of S cones is the only explanation I have seen on that.

[larsbrinkhoff]

Also, S cones are mostly found outside the fovea.