the more code you can understand and fix yourself, the less you’re held hostage to someone else’s failings.

The problem with that reasoning is that the more code you write yourself, the more you’re held hostage to your own failings. Much-used modules get a lot of people bumping into all of their quirks; your own code gets much fewer beatings and will take correspondingly longer to straighten out.

I’ve written about this elsewhere. There are good reasons to roll your own instead of using a module, but most of the time, the factors in favour of rolling your own are far outweighed by the factors in favour of using a module.

Makeshifts last the longest.