It doesn't stop providers from hosting it unmodified, or with modifications that they don't care about releasing—that's why Mongo switched from it, because other providers just provided hosting for it unmodified.
They're providing a service to people – and giving back their improvements, so you can then use them (though not in your proprietary version, if you have one, unless you negotiate that). Unless your business is in hosting versions of (the free version of) your program, problem solved.
