It doesn't matter if your guidance discourages it, your SEO algorithm is encouraging it. What you call "helpful" in your post is what is financially helpful to Google, not what's helpful to me.
There's no denying Google encourages long rambling nonsense over direct information
No one has demonstrated getting rid of "old" content somehow makes the rest of the site "fresh" and therefore ranks better. What's likely the case is that some people have updated content to make it more useful -- more up-to-date -- and the content being more helpful might, in turn, perform better. That's a much different thing that "if you have a lot of old content, the entire site is somehow old." And if you read the CNET memo, you'll see there's a confusion with these points.
But there's the rub, you're not making content more helpful. You're making it longer and more useless so we have to scroll down more so Google can rake in more ads. The fact that you're calling it more "helpful" is insidious. That's why garbage SEO sites are king on the internet right now. It's the same thing you guys do with Youtube, where you decreased monetization for videos under a certain length. Now every content creator is encouraged to artificially inflate the length of their video for more ads.
You're financially rewarding people for hiding information.
There's no denying Google encourages long rambling nonsense over direct information