[thesephist]

I think there's truth to both. A great example of the second kind is Chrome Devtools (or firebug, or insert-other-browser-equivalent-here, but I think Chrome leads the pack here). Chrome's developer tools is a gold mine of incredibly useful tools for profiling, measuring, and understanding complex frontend applications, and most developers only use a tiny fraction of the features it offers. Learning devtools deeply has been one of the most worthwhile investments of my time in my short dev career.

But the reason I lean towards build-your-own is that, especially for libraries and dependencies, popular tools that are "production-ready" also tend to aggregate over time features that everybody wants, but might not be useful to me personally -- it's hard to stay focused while growing to be the dominant tool in the industry. And that also makes it difficult to understand it completely. I think I understand React _well_, but wouldn't dare say I understand it completely; I can confidently say I understand every single line of Torus, because I maintain all ~1000 lines of it. And that makes it easier to stay in "the flow" when working.