But the features from the best programs were seldom if ever present in others— each program tackled interface problems in pretty much its own way. A keyboard combination that saved a file in one program might delete a word in another. You couldn't even quit a program in a standard way. Every time a user purchased a new program, he or she had to scale a fresh learning curve.
— Levy, Steven (2012-01-16). Insanely Great: The Life and Times of Macintosh, the Computer that changed Everything (p. 134). Kindle Edition.
This quote is describing the state of application UI on the Apple II. It strikes me that this is very similar to the current state of UI on the Web. Later, Apple rereleased the Macintosh and the Human Interface Guidelines to describe the common interface elements that all Mac applications would share.
I wonder if a similar consolidation of common UI elements will happen for the Web. There are various frameworks or boilerplates that provide this, but nothing that is truly common. For this to happen, I think browsers will need to include more common UI elements beyond what is currently available in HTML & the DOM. If I had to bet, I'd put my money on Chrome heading in this direction.