You're speaking of a whole other kettle of fish. You had high volume servers providing mail service for barely trusted users. This post is about one mail server providing service for, presumably, one guy. It's entirely possible to reliably send mail to Yahoo if you control the server. In fact, it's not even that hard. I've explained how in another post.
We have a few hundred (mostly small) hosting providers running our software which includes a mail processing stack, and quite frequently they ask about stuff like this (and yes, Yahoo comes up more than GMail, but about the same as Hotmail). And, there is very often anger involved, just as in this case. But, the fact is...if you follow RFCs strictly (Zed has written his own newfangled mail server in Python; I suspect he's made some mistakes, as the mail RFCs are notoriously difficult to get right, though the MTA isn't necessarily dealing with all of the messiness of the protocols), have DNS that resolves in both directions, and have accurate SPF records, delivering to Yahoo will work reliably and fast.
We've occasionally gotten comments that DKIM is necessary to deliver to Yahoo, but whenever I hear it, I'm surprised to hear that a major provider has finally started actually blocking on DKIM. So, I go check. I always find that no, DKIM is still not required to deliver to Yahoo. It probably helps, though.
I'm not saying Yahoo doesn't have an itchy trigger finger on the blacklisting process. Maybe they do. They certainly aren't as good as Google at non-obtrusively, but effectively, blocking spam, but very few providers are.