Intel had the margin and volume to be the exception to the rule, meanwhile Qualcomm, Broadcom, and a ton of other fabless design firms were making good money unencumbered by the risk of investing in a fab division, and with the ability to switch to the best fab for each chip at a given time.
So I don't think it's as direct a link as you seem to claim. Maybe it was the right decision if AMD had the money to keep it going. But it will likely forever be one of those questions that has no solid answer either way.