'AND THEY WILL ALWAYS DO IT CHEAPER BECAUSE THEY DONT HAVE TO FUND FURTHER DEVELOPMENT.'
Well, they DID actually contribute patches as the whole ES project was 'upstream-first', this is mentioned in the post with proofs.
From what I can find online, it looks like DocumentDB is actually a layer on top of the AWS Aurora PostgreSQL offering. This means they created a MongoDB compatible API, but are not offering a hosted mongodb cluster. (https://news.ycombinator.com/item?id=18870397)
Without wanting to come down on either side of the argument I'd like to say that the Pull Requests they reference in the blog post are over a span of roughly two years and touched somewhere in the vicinity of 1k lines of code. One of them changed one line by adding a synchronized modifier to a function..
I'd not consider that actively developing a product and adding new features.
From what I can find online, it looks like DocumentDB is actually a layer on top of the AWS Aurora PostgreSQL offering. This means they created a MongoDB compatible API, but are not offering a hosted mongodb cluster. (https://news.ycombinator.com/item?id=18870397)