If PR is good, maintainer refunds you ;)
I noticed the same thing in communication. Communication is now so frictionless, that almost all the communication I receive is low quality. If it cost more to communicate, the quality would increase.
But the value of low quality communication is not zero: it is actively harmful, because it eats your time.
You can also integrate it in clients by adding payment/reward claim headers.
So the paywall email firewall will not work as desired.