bollocks, that's because javascript doesn't have a standard lib.
> You do know we hire people who have to _write_ these libraries
I know, because I'm there. I'm working in VR/AR. We have a number of people who are world experts for doing what they are doing. Do I go off and re-make a SLAM library because I don't like the layout? no because I have to ship something useable in a normal time frame. I can't just drop 3 months replicating someone else's work because I think the layout is a bit shit, or I can't be bothered to read the docs (I mean obviously there are no docs, but thats a different problem)
But, and I cannot stress this enough, having more than one person making similar or related libraries is a disaster. Nothing gets shipped and everything is devoted to "improving" the competing libraries.
If I ask you a question along the lines of "write me a function to tell if two number ranges intersect" and your solution is to grab a library instead of writing a simple predicate...then perhaps the role is not a good fit.
"Use a library for everything" is how we ended up with left-pad on npm.