And this is how you end up with rewriting the world and spending more time rewriting dozens of existing libraries to avoid adding them as dependencies and less time working on the problem you're actually trying to solve because you're fixing the same dozen bugs that the first person already went through the trouble of fixing for you had you simply used their library instead of eschewing it and having to learn everything that they had already learned for you. Often times because the problem space is deeper than you could have known before getting into the weeds and hopefully you don't get bit by sunk cost and decide to do yourself a favor and just use a library instead of continuing to work on solving problems that aren't related to what you set out to do.

There's a balance to be struck between LeftPad scenarios and "Now there are 37 competing libraries".