I fully agree that AWS should do a better job of contributing back to OSS communities both in terms of code, money and man hours, however I don't think most ppl appreciate that a lot of AWS' secret sauce just doesn't make sense to open source even if they wanted to.
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?