Routers, switches and repeaters in the middle are serving nothing, they are relaying IP packets at the transport layer.
If you can’t tell the difference, you may want to read up on basic network layers.
This is why Google is analogous to Comcast here. Neither can mess with the content or impact its origin. They are just part of the packet transmission system in between.
Hence this is a huge win. Previously, AMP was served off of Google servers where Google was the man in the middle aware of and even able to manipulate the content. The scripts were running on their origin, etc.
Now with this signed exchange tech, the contract is between browser and origin server. The Google cache is now super dumb, which is a big improvement from a privacy and security perspective.
Transparently serving content from google when the url says something else is a complete loss of privacy and security from a user-perspective.
That’s a massive loss of privacy right there. How is that even debatable?
Also given how Google works, I think it’s reasonable to assume that enabling this additional Google-tracking was the primary intention behind AMP.
My isp cannot do that because the url is part of an encrypted transfer, but a transfer google now has allowed themselves to snoop into.