We don't all agree what a solution needs to address. Application consists of n web pages and need to target m devices, giving rise to a n times m problem. Exhaustive approach doesn't scale. But this not required in all applications.
Application model has to address state, interaction and transactions.
Not all applications will use all of these. Another approach is to embed information about presentation and interaction into the content. Constraint-based mechanisms can simplify the task of the author by pushing the burden back on the implementors.