That's really unfortunate. I think education is the best place to teach these things bottom up. Especially considering that you understand a framework way better after creating one yourself. There are not that many essential parts in a web framework anyways, it's the plumbing, the tooling and the polish around them that makes them productive.
Exactly. IMO you're a 100x better developer when you at least tried to create something you use from scratch.
I find however this will become harder and harder with newbies being constantly bombarded online with messages stating that creating anything from scratch is a futile exercise, together with companies influencing college curriculums.