I agree with essentially everything you said. While reinventing the wheel isn't always to most efficient solution, such actions have sometimes paid dividends in my past.

> People need to be more curious, and strive to be more knowledgeable.

Absolutely, though I am not sure lack of curiosity nor strive is always the issue. It's one thing to green field one's own solution in an attempt to better one's abilities, but it's also a bit idealistic in a working world of impending deadlines and death-march Agile sprints.

In this case, a 25 line function to solve a constraint would likely take me far less time than grokking an external library's documentation, but in many cases, I feel developers jump on external dependencies because time is of the essence.