Do Not Link allows you to ethically criticize bad content
When you criticise an article on a horrible site and link so people can see the original page, search engines see that as “someone is interested in this page”.
And activity by people criticising the page looks just like activity by people liking it.
So the horrible site goes up the Google search results. And the horrible site goes “whooo, lots of hits and links, guess that article was popular” and decides to create more horrible articles like it.
When you’re linking to horrible sites use Do Not Link: from the user end it works like tinyurl or bit.ly, but it doesn’t give the website attention.