Yup. As more and more domains centralize email in the handful of mega-corp hosted solutions the hosts have less and less reason to care about accepting mail from outside the walled gardens.

It's not about setting up perfect signed email and all the new techs. It's not about having the same clean IP for a decade. It's just the same old network effect combined with profit motive. The obvious change in the last few years (I've run a mailserver for 9) is managerial not technical.