Look clearly you have zero understanding of how enterprises work. And given you have added Hazelcast which is a distributed in-memory solution in there shows you have a poor understanding of technology as well.
It is all about support. Big companies have operations teams who manage infrastructure and deployments. They aren't experts in databases and so want to be able to ring someone who can help them when the times get tough. 10gen understands this and have a great support story to talk about hence their popularity. Most OSS don't.
a simple fact that you get defensive and personal reveals that you are not happy with your confidence level. but that's ok, as you get more mature, and acquire a certain perception depth (and I wish you do), you'll prefer being constructive vs. angry.
I didn't mean to hurt your feelings. Hazelcast solves similar problem that all of the valuations in the list: "storing and retrieving data". By the way, "file system" does it too (let's valuate it as well @ $3.6B).
As far as "enterprise support" in case of Mongo, it's like running a political campaign: nobody really knows "who" is inside, until "he" gets elected, and when "he" does, the "support" needs to make sure reality stays hidden, by white (and not so white) lies. And yes, MongoDB is great at "support", most OSS aren't.
It is all about support. Big companies have operations teams who manage infrastructure and deployments. They aren't experts in databases and so want to be able to ring someone who can help them when the times get tough. 10gen understands this and have a great support story to talk about hence their popularity. Most OSS don't.