Isn't the whole point of PAAS/IAAS offerings the idea that someone else is responsible for maintaining the underlying platform/infrastructure? Not trying to cut down your idea; just trying to get a better understanding of some typical use cases.
My use case, specifically, is that I have one app that has a large amount of personal data in it, and another one that doesn't fit under the terms of use of any of the PaaS providers. They're not going to get any traffic outside of me and a few other people and it's totally fine if they aren't available from time to time.
By using Foreman and Mason in my own environment, I get to use the patterns that those tools provide (buildpacks, Procfiles) outside of Heroku.
I'd add that some of us know how dishonest people work, and would never give control of critical items to third parties (because everyone has their price.)
Thanks, and looking forward to trying it out.