Correct. It's ISN'T DSA. It's very promising for eCommerce sites which may have a personalized header (Name, Cart Contents, etc...) and some customized Ads/CT

Correct. It's ISN'T DSA. It's very promising for eCommerce sites which may have a personalized header (Name, Cart Contents, etc...) and some customized Ads/CTAs/Marketing slots, but where the bulk of the page (often a very large page - 100+ KB) will be the same for everyone. The obvious win is pushing less bytes across the wire. The less obvious win is that it allows the application server response to complete VERY fast, freeing up the app server thread to handle more requests. This is the larger win for large scale 3-tier applications.