I know this is a blunt and harsh statement to make, but when you sell a service, you have zero native incentives to Open Source the way your system works. It just opens up Competition. This is not unique to AWS/Amazon. But their success gives them the power to have wide OSS damage.
This is, to me, the biggest reason why cloud portability should be something that every customer of a cloud service should have in their plans. Amazon as a company has shown no timidness in both "embracing, extending, extinguishing" their competition.
OSS literally built the internet and opened up the wold wild communication age, let's not be so short sighted that we don't see proliferation of cloud services ( specifically one having so much dominance), for what it really is.
[0] http://dtrace.org/blogs/bmc/2018/12/14/open-source-confronts...