While I agree with your point, and think AMP should not need to exist, Signed HTTP exchange might actually be great for other types of very cheap, dumb caches o

While I agree with your point, and think AMP should not need to exist, Signed HTTP exchange might actually be great for other types of very cheap, dumb caches or CDNs that only have to rehost one file to cache a page, and not even serve it through SSL. I know I might use it as a web designer to send interactive snapshots of how the website currently looks/works to the client; instead of using an ephemeral URL and a tunnelling/proxy service.