I think the fact that it's already been done doesn't eliminate the need to learn it. It just changes the order in which things should be taught and learned. People used to learn data structures first, because these were the components from which they would build their programs. But Java, for example, has just about every general-purpose data structure you could possibly want in its standard library. So you can start writing your own programs using the standard implementations of Map or Set or List. Later, when you want to learn more or you find that one of your programs isn't as efficient as you'd like, you can delve into the gritty details.