Not necessarily. It could also mean that these functions are more specific, have names that make sense in the concrete context and don't have any unnecessary parameters you need to think about. When it comes to ORMs it's even worse. They are often not libraries but frameworks with tons of non-local settings and state you need to know about (or else...).

Not invented here also means not invented for the specific task at hand but for a much more general set of use cases. In my view it's a trade-off, not a fallacy.