I disagree - most publishers I've seen (including large and mid-level) have some of the most bloated HTML with megabytes(!) of javascript and CSS just for rendering + all the other stuff you mentioned. They are definitely not optimized.

I dont think there is any innovation at all with either Facebook or Google, it's all about keeping the user on their service longer and by hosting the content themselves, they increase speed and claim more user time. It's a pure monopoly play with Apple, Google, Facebook having far more leverage than publishers (who have really none these days). Pubs need traffic to survive which is why they are willing to work with this, but the revenue potential is still up in the air so long-term sustainability is not anywhere near proven. I'm not convinced that this will work as a viable model, beyond the technical implementation.