What a bunch of nonsense being propagated around this, see https://techcrunch.com/2019/01/09/aws-gives-open-source-the-middle-finger/
A few things to remember:
* They are implementing the MongoDB *API*, not the MongoDB code. Hardly surprising, since MongoDB is in fact shit, and won't scale to AWS volumes.
* It's rather misleading to paint the MongoDB folks as the poor victims here, as in "MongoDB was one of the first companies that aimed to put a stop to this". Rather, MongoDB relicensed to something of their own making which is rather less than open.
Don't believe the hype. MongoDB is very popular even though it's crap; competition in their own front yard is *exactly* what is needed here.