[stared]

There is always balance with reinventing the wheel. Plus, a custom library often gives way more technical debt than a standard one. Less battle-tested, fewer tutorials, very often a lot of idiosyncrasies.

A few times, we were going a different route:

We use libraries if needed, but after some time, we pruned ones from which we used only a few functions/classes. That way, there is (almost) no delay in development, but there is this process to keep things clean.

The converse is much more challenging. Writing a lot of code then discovering one is effectively reimplementing an existing library, which took quite a few person-years.