> But isn't using the code that people smarter/more proficient than you have developed a rather good way to go about things?

Many problems don't go away and don't become easier just beacuse you shove them under the carpet into a library. A lot of developers use libraries as an excuse to NOT THINK about the issues and ignore their existence not to save work. There's a fundamental difference between "I understand the problem and I know that library X will give me a good solution with low amount of work" and "This problem is hard, I'll shovel in another library and keep my fingers crossed that it does a good job at it."

It's saving work vs. saving thinking. First one is ok. Second one is not.