They <i>do</i> use your likes to tailor content, which someone explored (with hilarious effects) by liking literally everything in his feed for 48 hours: <a href="http:&#x2F;&#x2F;www.wired.com&#x2F;2014&#x2F;08&#x2F;i-liked-everything-i-saw-on-facebook-for-two-days-heres-what-it-did-to-me&#x2F;" rel="nofollow">http:&#x2F;&#x2F;www.wired.com&#x2F;2014&#x2F;08&#x2F;i-liked-everything-i-saw-on-fac...</a>