I left Amazon a bit over a year ago, after being there seven years. It always struck me as a combination of "not invented here" syndrome and a solution in search of a problem. It has no real world benefits over JSON, the tooling is limited, but you inevitably have to deal with some other team that regrets choosing it and now it's their API. I'm so happy I never have to look at it ever again, and seeing this post today is a real throwback to wasted engineering effort. Just let out go, Amazon.