Libraries are much harder than applications because they must work for a large number of applications with diverse requirements. They need to be more abstract, and therein lies the danger.

Regarding the size, clearly wrong. It depends a lot on the library. A windowing or font rastering library will be a lot larger than your typical application.

And for libraries that are much smaller than the application itself, why bother depending on them? (Anecdote, I heard the Excel team in the 90s had their own compiler).