> I can't help but think this mentality is what lead to the recent left-pad debacle
It borders on category error to compare homebrewing argument parsing with an overreliance on microframeworks extending all the way down to leftpad. Argument parsing is almost always supported directly by the language implementers in a standard library. And even if it wasn't, it's such a critical task with huge overhead for handling corner cases, cross-platform details, etc., that the value of a central implementation is obvious. A left pad operation ought to be part of the standard language (which is actually what the leftpad debacle was about, Javascript's incredible failures as a language), but it's too trivial to compare it to something like argument parsing.
> The pseudo-code of BFS is all of 20 lines, ...
If it's only 20 lines, that's great because it means it was easy for the other 500 library writers to write it, write tests, and observe and fix issues over time. So, whew, that's 20 lines I totally shouldn't waste my time on, plus unit tests and routine maintenance I don't have to commit to.
And also, given the wide acknowledgement that a good programmer should be writing at most a few hundred lines of code per day (otherwise it's probably mostly junk), 20 lines of code is not trivial.
Probably most programmers write a whole lot more than that per day (especially if counting copy/pasted code), but this is in part a sign of a bad programmer, or perhaps more so a sign of the anti-quality constraints placed on them by most employers.