[smnrchrds]

The idea is not that everyone would implement the entire functionality of every library they would otherwise use. With big libraries, each user may need 5% of the functionality. But not the same 5%. If the options were paying thousands of dollars or implementing your own, in many cases the latter would make sense. Definitely not in all cases, I admit.

The way I think about it is what if the only database solution was Oracle. I'm sure many would have wrote their own limited buggy DBMS or used flat files instead. It will certainly be more expensive to write your own Oracle RDBMS from scratch instead of paying for the licence. But you don't need most of the features and for the ones you need, the price point does not make sense for all projects. For some projects, flat files or JSON files saved somewhere on the disk wouldn't sound so bad.