Soft 404 Crawl Error Search Spam- what’s the point?

I was reading the post below by Zwielicht. I am curious what the point of doing this spam? Does it hurt their rankings? Or it like the analytics spam that goes on? Just an advertisement? Love to hear thoughts and theories.

https://www.blackhatworld.com/seo/3-years-on-bhw-the-only-seo-guide-thats-worth-your-time.873651

Soft 404 Crawl Error Search Spam- what's the point?