It literally does have that option - go to their profile, click the "friend" dropdown, change it from "friend" to "acquaintance", see that they stop showing up in your feed :)
http://www.bewebsmart.com/social-media/facebook/use-the-acqu...
How does that work out for you? I could never get Facebook to give me a usable news feed. I unfollow friends, pages, like new pages, intentionally scroll through new pages and like random things in order to get its posts on my newsfeed, adding people as my "close friends", blocking random pages that are on my newsfeed for bullshit reasons ("John Doe and 2 other friends like this post") and I could still never get anything even remotely useful, neither by adding the data, nor by reducing the number of data.
The latest pitfall I'm having is "a video that you may like". It started appearing like less than seven days ago, and in every single example, it's just some bullshit video from a page that I have never liked, but have interacted with in the past once or twice.
A large percentage of my feed is from pages for video games and tech companies/software. It's possible my interests align better with how they select stories for my feed than yours?