I was wondering about this, as it's not explicit in the article: What is the business model that makes money for Docker and MongoDB? From MongoDB's website I gather they have some "Enterprise" things, but they want me to give them my personal data just to access a "datasheet" describing this. Docker's "Enterprise" offering seems to be a mix of support and hosting.
So is that it? Support, hosting, and donations from Big Business?
The article also says: "Thousands of people used RethinkDB, often in business contexts, but most were willing to pay less for the lifetime of usage than the price of a single Starbucks coffee", but I don't understand what those users would have payed for. What was the product being sold? All I can gather from the article is some cloudy hosty database-as-a-service thing that might have made money but never shipped.
This is a variation of the "no one ever got fired for IBM" trope, and is in fact a big moneymaker for the likes of IBM, Oracle, Microsoft, and the like, even in situations where the standard notions of vendor lock-in may not even apply.