"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"<p>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.<p>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 <i>how</i> and <i>why</i> they are built the way they are built.