I think your comment and perspective hit the heart of the matter. You view your work in isolation. And if you're not working in isolation, you are assuming that

I think your comment and perspective hit the heart of the matter. You view your work in isolation. And if you're not working in isolation, you are assuming that your co-workers are in the 99th percentile of coders. If you're making some small webapp or mobile app, then that mentality is fine. But think about it from a different perspective. Let's imagine you are hired by a company to come in and build a large, web-based, responsive, buzzword, buzzword application for them. It's big enough that it is going to take months to develop and require numerous developers. The strategy of "just writing a JS file and adding a script tag to their html, that's how most of us learned it." is not gonna fly. And if you are spending your time doing "If you can't find what you want, build it yourself, maintain it, and use it" then how are you getting your actual application done? You don't want your devs spending a month of time to build (and then support) some templating library or some such when your real task is to write some kind of CRM application. So how do you go about picking technologies, training teams, building upon existing libraries, etc. in order to build your actual product?