I really like this side to AMD. There's a strategic call somewhere high up to bias towards collaboration with other companies. Sharing the fabric specifications with broadcom was an amazing thing to see. It's not out of the question that we'll see single chips with chiplets made by different companies attached together.
Maybe they feel threatened by ARM on mobile and Intel on desktop / server. Companies that think they're first try to monopolize. Companies that think they're second try to cooperate.
IBM didn't want to rely solely on Intel when introducing PCs so it forced Intel to share its arch with another manufacturer that turned out to be AMD. It's not like AMD stole it. Math coprocessor was in turn invented by AMD (Am9511, Am9512) and licensed by Intel (8231, 8232).
They certainly didn't steal it. But Intel didn't second-source pentiums, or any chip with SIMD extension. AMD reverse-engineered those fair and square.
