I disagree (mostly). What’s the difference between library and language built-in? PHP and C++ has a ton of built-ins. It doesn’t make it less complex than using library.
Problems that look simple at the first glance are in most cases are complex with too many edge cases.
I think I have never written a single utility function that had no non-obvious bug, and imagine that in more complex problems
Not to mention in many cases any function you write is possibly dangerous.
Just take a look how many things you have to consider when checking for odd number in JS:
https://www.npmjs.com/package/is-odd?activeTab=code
And of course most of that can be fixed be using strongly typed language.
If you’re a beginner:
I almost gave up programming once, I thought I was too stupid.
Then I learned Linux and figured out starting out in IDEs as a beginner is the worst thing you can do. It doesn’t teach you anything, it just lets you get the job done - the thing that you should avoid while learning.
If you can’t build your software with only CLI - you probably have no idea how technology you’re programming in works.
If you are intermediate:
Reinventing the wheel is a great way to learn how libraries you’re using actually work.