If the blog were about calculus, and stated that an elegant proof of the Fundamental Theorem of Calculus could be found in such and such undergraduate textbook, would you be upset that the citation wasn't to either Newton's or Leibniz' work?
I would want them to point to point to what they think is the best resource. (Assuming the point is educating or explaining something to the reader.) Which, If everyone followed, would automatically point back to newton/leibnez.
Upset no.
But I would like it to be a violation of norms around citation. We should respect the reader and the truth.