Open source takes work and the foresight to separate your custom shit from things genuinely helpful to the community. Amazon doesn't encourage or incentivize that kind of thinking.
That is exactly what AWS has done in releasing Firecracker[1]. Better late than never.
Releasing stuff isn't simple, the hosted services only work because of the rest of their infrastructure. Writing about the tech is usually the best way to spur clean open-source versions that we can all use.
From what I recall DynamoDB is a somewhat hacky API layer over a bunch of MySQL clusters. I'm not sure anyone would, or should, attempt to use a non-managed version of it.
The recent MySQL info comes from this 2016 thread on DynamoDB storing empty strings: https://news.ycombinator.com/item?id=13170746
Confirmed by this comment specifically: https://news.ycombinator.com/item?id=13173927
The latest 2018 ReInvent deep dive on DynamoDB doesn't reveal anything but still fits if mysql is powering the storage nodes: https://www.youtube.com/watch?v=yvBR71D0nAQ
But there is more to this as well. AWS is a huge ecosystem by itself, a lot their services intertwined with each other, simply open source DynamoDB isn't enough without open sourcing the networking/storage functionality that is probably provided by other services.
They build their own custom nitro ASICs to integrate with KVM, for networking, storage, security, etc. That code doesn't make sense anywhere but AWS. They build things in ways that are tightly integrated with their internal systems and at a scale that few have experience with.
Take their new Envoy based service mesh for example, I really do hope that they make meaningful contributions back to the main project, but I also suspect they will doing lots of custom integration with their own hardware and internal network that will never make sense to support in an OSS project. Who knows, their Annapurna Labs divsion might even be building a custom card that includes Envoy functionality.
As to them being known for destroying OSS businesses I am drawing a blank there, can you provide some examples?