My guess is they felt they didn't have a choice. Having worked at a company with a very large AWS bill in the past, they actually listen to what their customers

My guess is they felt they didn't have a choice. Having worked at a company with a very large AWS bill in the past, they actually listen to what their customers want. I also think it's clear that most cloud-going engineers and decision makers wanted a solution like k8s and "native" cloud support for it. If they had chosen to use their own proprietary platform they risk Google and MSFT peeling customers away who want to work on a well designed open and portable orchestration platform. That might start slow but Amazon didn't get this big by allowing competition to take customers without throwing their own punches. They could have made their own _open source_ platform that would directly compete against k8s but by the time it was clear that demand was huge (I'm thinking early 2016) k8s already had to ton of momentum. Again they probably saw that and figured this was the best move with a high probability of success, even if it meant less lock-in. They also have a whole slew of other products that serve almost exclusively as lock-in mechanisms. One truly portable product isn't going to be a huge deal. EDIT: Distinguish proprietary and open source options in the second paragraph.