Yet more special pleading.
This argument might make sense if it was claimed that Google, Yahoo
etc were doing this for some corporate agenda. But I am pretty certain
that is not the case here. Google, Yahoo etc. are doing this because
they think it is in the interests of their customers because they
believe it will reduce spam.
A legitimate argument against DMARC would be 'Here is a research study
based on empirical evidence that shows DMARC does not help'', it might
not be persuasive but it would be a valid argument to have. I am
certain that the Google, Yahoo, Microsoft, etc. folk have those
studies.
So what is the argument being made against? I see a lot of
hypotheticals and I see a lot of people arguing that the real problem
here is that Google, Yahoo and Microsoft are putting what they
consider to be the best interests of their customers ahead of
compliance with purported IETF diktats.
I find the arguments that IETF should ignore the impact of DMARC
unpersuasive. We have changed email repeatedly in response to non
standards compliant actions taken by the spam senders. So there is a
precedent for responding to malicious actions, why would we treat
non-malicious actions differently?
We are engineers, not priests. If people think DMARC is creating a
problem then explain the problem precisely and find a solution.