Comment by sowbug
I'm reminded of Larry Wall's advice that programs should be "strict in what they emit, and liberal in what they accept." Which, to the extent the world follows this philosophy, has caused no end of misery. Scrapers are just recognizing reality and being liberal in what they accept.
I think it's Jon Postel who was the original source of the principle (it's often called Postel's Law). https://www.rfc-editor.org/rfc/rfc761#section-2.10 is an example dating back to 1980.