> GUIs are successful when they follow visual and behaviorial standards.

Wouldn't that be a design or HCI issue, not something innate to a language? What is a behavioral standard?

Yes technically but the language enables it.

A behavioral standard would be that scrolling always works by sliding the scroll bar or using the arrow or page-down keys.

Or that the back button takes you to the previous page.

Just two examples.

Many sites break these and you have to discover what they replaced them with.