I'm guessing these license models are all because they want to just plainly sell their own instances without cloud providers competing with them directly (who typically have unlimited resources to do so!) or keeping any changes or fixes to themselves (I think that was the reasoning with Mongo?).
Offtopic / Meta to the article itself:
What is with the format of this article, like if they meant for the stuff in brackets to be headings, but chose this format instead of making them headings.