Ian Hickson píše:
While every USER has to be catered for, the same is not true for every possible use case from the content producer side. For example, at the moment it is not in the scope of HTML to handle writing photo editing applications like Photoshop or movie editing applications like Final Cut Pro. While it may be possible to write such applications in HTML today if you are rather masochistic, it is not something that HTML makes easy, and it is not likely that we will make it easy in HTML5.
We want to keep the language as simple as possible while still catering to the majority of content producers (and while catering to all users).
Note that the "80" value is arbitrary. It is just meant to symbolise the fact that we don't want to cater to all use cases, we only want to cater to the most common ones.