I have a question about the original W3C Recommendation (for annevk, maybe ?). The rec was quite prescriptive about server-side processing. In particular

If the value of the Origin header is not a case-sensitive match for any of the values in list of origins, do not set any additional headers and terminate this set of steps.

(source: https://www.w3.org/TR/2014/REC-cors-20140116/#resource-processing-model.)

Unless I'm missing something, I see no such prescription in the current Fetch standard (which is for the best, I believe). Out of curiosity, though, what motivated that less prescriptive stance? (If necessary, I can provide more context for my question.)