At any large media organization, there are tremendous amounts of content no longer connected to any CMS that may have hard-coded insecure links/resources in them. Some of them may live on obscure servers or domains. Or the developers/journalists who worked on them and have knowledge of their construction are long gone. These pages are very laborious to find and update.

If you don't mind 404ing or breaking a ton of your old content, it's probably not too difficult. But if you're the newspaper of record, it's a big deal that URLs live on and continue to work as expected.