[djeric3]

To be fair, pretty much any platform (operating system) provides rich APIs and basic functionality like built-in UI components. So I don't think there's a lot more pre-existing functionality in a browser vs Windows or Android.

[codedokode]

I think you are wrong. Windows API compared to HTML APIs are very low-level. For example, there is no automatic layout and you must specify exact size and position of every GUI element like button or input field.

[true_religion]

Some apps use a GUI framework, and don't combine it with their app into a single file, which makes for a better comparison (e.g. Paltalk does this).