A lot of dynamic sites use Fastly for its programmatic edge control and a near immediate ( ~1s-4s, typically around 2 ) global cache invalidation for any tagged objects with a single call to the tag. That feature alone simplifies backend logic significantly. To make this feature portable to CDNs that do not support it and provide only regular cache invalidation requires a complicated workflow setup which significantly increases the cache bust time, which in turn removes all the advantages of the treat dynamic content as static and cache bust on write approach.
