I think the key problem is ISPs that do not block egress traffic on port 25. If you need to send mail through a different SMTP server than provided by your ISP, the admin of that server ought to provide you with a means of using it with authentication on a port other than 25
At least it was on slashdot so people know it's moronic, but good god what a prat. Because the email system is open to abuse, we should split the world in two (those deemed 'good enough' to send email and those who aren't)? Of course, the difference between those two classes would be that the former have more money. I just don't want to start on what a bad idea that is.
(Incidently, that does the same thing that blacklists now do, but at the other end and I think those blacklists are equally moronic.)