It's simply not true we have no incentive to fix this. Here are a few:
Firstly, Gmail's success is entirely predicated on the health of the global email ecosystem. Gmail does not, inherently, have any network effects (unlike FB, messengers, any other comms tool of Gmail's scale). Email itself, of course has a huge network effect, and that is because you can email anyone in the world, regardless of what email system they use. It's because email is open. If we lose an open, healthy ecosystem with many providers, we'll destroy the base we stand on.
Secondly, we care deeply about having positive relationships with developers and all our users. I can tell you it definitely makes me sad to see articles like this. There are going to be false positives, we will make mistakes, but we certainly care a lot about fixing issues like this when we hear about them.
I agree Postmaster tools has been underinvested in and we could do much better there.