Comment by dingnuts
when I read the spec it seemed like the operator of an AppView & Relay would be most in need of compensation for their hosting costs due to the amount of demand on those components so I believe the spec allows an operator to implement their own AppView & monetize it as that operator sees fit, so that they can afford to operate the service and maybe even make money off of it so that they can make it their full time jobs.
It seems this way to me as well. ATProto fundamentally changes how monetization works in social media by removing lockin. It's going to be interesting to see what emerges from this design decision.
Another interesting way to view ATProto is that it could be a collection of headless features and network browsers that leverage those feature providers.