The components that are given are "building blocks" Buttons, "cards", dialogs, text input fields, etc...

Once you get them, you can just override the color, size, shape, and sometimes a few other little things and it "just works".

So I don't need to worry about getting an input box to correctly style on all platforms, I don't need to come up with the animations and JS to make the fancy "floating input field" or the inky splash effects or the 2-step shadows.

That's also why the issue around styling these things is so contentious. It's a major way that you'll be interacting with them, and with the way CSS works it's not easy to "overwrite" default styles without using !important which feels like using a sledgehammer to crack an egg.

We aren't designers, and being developers we have a tendency to nitpick which is only worse when the subject is just outside our area of expertise...

Picking a design "platform" and using a toolkit to implement it pretty much stopped most of that in it's tracks and let us focus on the actual application.

It's obviously not for everyone, but it was exactly what we wanted and needed.