It's one of those ideas that sounds great when you hear about it in college, but doesn't really work when you try it in practice. "Universal" data abstraction layers like ODBC and object-relational mappers like Hibernate, Django, SQLAlchemy, etc. have been around at least since the mid-90s and perhaps before.
The problem is that all those inconsequential differences between data stores are really important. The article explicitly says "Scalability and performance are outside the scope of this", but in real-world software, scalability and performance matter a lot. When we'd tried out Hibernate for a past employer, performance dropped by 80% - data operations were now taking 5x as long to complete. You can recover much of that by tuning your mappings, but by then, you're pretty much writing SQL anyway, and your app wouldn't work with any database other than the one you tuned for.
Also, nearly every app needs its own data abstraction layer, one that works with the particular operations and domain objects of the app rather than tuples and records and tables. At this point, there's little reason to go through another abstraction layer, adding complexity and slowness to your program, when your calls to the data store are already localized to one module.
The problem is that all those inconsequential differences between data stores are really important. The article explicitly says "Scalability and performance are outside the scope of this", but in real-world software, scalability and performance matter a lot. When we'd tried out Hibernate for a past employer, performance dropped by 80% - data operations were now taking 5x as long to complete. You can recover much of that by tuning your mappings, but by then, you're pretty much writing SQL anyway, and your app wouldn't work with any database other than the one you tuned for.
Also, nearly every app needs its own data abstraction layer, one that works with the particular operations and domain objects of the app rather than tuples and records and tables. At this point, there's little reason to go through another abstraction layer, adding complexity and slowness to your program, when your calls to the data store are already localized to one module.