One common fallacy of the NIH folk is that reinventing X package would take a lot of time.

But first, you will of course not remake every single feature, just the one you need.

And furthermore, when you code just one feature, you don't need to make any abstraction or additional function interfaces. So it's cheaper, and probably better integrated.

Another fallacy is that you'll make bugs and introduce vulnerabilities. Maybe, if you are a bad programmer, but you will also avoid a category of bugs where the vuln is introduced at the boundary of the integration between two different libraries that weren't designed to fit exactly together. (Many such cases)