"Now, I'm not saying that junior developers should go using their libraries for commercial usages. But for their own personal projects, the educational value is

"Now, I'm not saying that junior developers should go using their libraries for commercial usages. But for their own personal projects, the educational value is immeasurable" I totally agree with this. I have been learning and building web apps and I always try to re-invent the wheel just for my own purposes. Then I can always go back to more standard libraries. This I think is a very valuable and important point for people who want to learn. So I say "break things, re-invent, start from scratch to learn. Once you do that, using proven/tested/standard libraries will be a breeze because you will know how and why they are built the way they are built.