Only nerds care about non-native widgets.

Native widgets come with a bunch of accessibility and localization features that are typically missing from naive custom widgets.

A native English speaker with normal vision might naively assume that they could reimplement a widget that's just as good as the native one in less than a week, but the result will be awful for anyone who doesn't match that description.

If you're building with web tech accessibility and localization are easier to add to a custom widget (though they do still require thought), but this is Godot, not Electron.

I've read comments like this for years. But without concrete examples it doesn't stick.

And people with disabilities.

Accessibility can be implemented for third party GUI toolkits.

Qt: https://doc.qt.io/qt-6/accessible.html

Web: https://developer.mozilla.org/en-US/docs/Web/Accessibility

Even immediate mode toolkits can do it: https://news.ycombinator.com/item?id=33859697

Accessibility is not a reason to use first party widgets. It's a reason to use widgets with good accessibility support.

In theory, in practice the myriad of devices and software is rarely tested or works properly beyond official mac and windows interfaces, and maybe gtk and qt if you're very lucky.