Yes really. With DKIM, you blacklist domains, not IPs. Of course, only if you do it properly. Hotmail doesn't...

You're pretending that domains aren't a cheap disposable commodity, they are.

That's to be expected. All it does is ensure the accuracy of the email sender. Which finally lets you attach reputation to domains instead of addresses.

Because most email providers will block you if yo don't have them now. And because of that, if you get blacklisted you need to buy a new domain, not just a new ip address.