See this is the whole point of what Facebook (and much of the web that makes money off of advertising) is trying to do. The end goal is to make ads that don't LOOK like ads, and they have gotten pretty good at it. Nobody liked ads before because they were intrusive, obnoxious, and weren't relevant. Slowly, they have become less of all of these things to the point that tons of these ads look just like regular posts, especially on the mobile platform. Think the subliminal branding advertisements in movies, where the cars all all BMWs and phones are all branded by Samsung etc.

It's just like how some blog posts look like travel posts, but in reality its just a credit card advertisements, or try to sell you some "must have travel accessories." People are more likely to read and click on an advertisement if it doesn't look like one at first.