Why do people feel so compelled to create their own custom components when the component library you're already using HAS ONE ALREADY?!

You can change the styling and animations using CSS and props. Stop building buggy shit from scratch.

Kinda depends.

If I need something stupid ass simple sometimes I like making something I know exactly what it will do 1000% of the time...

Granted, that's rare.

We mostly make middlewares so we can always swap the library.

@N00bPancakes yeah sure, however, this dev's logic was "the button is on the wrong side and I want to add an animation for when the component expands so I'm going to write my own". There's an onExpand callback in the component already...

Because it's the easy option.

It's not the best option, nor is it the most concise, nor the most bug free. But it's easier to hack something together from scratch than it is to learn how to use your framework to do the same thing.

I think some devs are just bad at looking into options for existing components, so maybe he didn't really consider it could have an onExpand. This could be a result of having worked in previous projects with bad component libs that gave them the habit of assuming a component isn't easily modifiable.

Additional functionality and reusability?

Depends on how much my salary is