Social media advertisement is the sales guy sitting down at your table in the bar and trying to sell you a new refrigerator when you're hanging with friends because he saw you looking at refrigerators two weeks ago in a shop.
Search or content related advertising is the sales guy trying to sell you a new refrigerator when you're looking at refrigerators.
One of those has a chance to make a sale and might even be appreciated. The other is just irrelevant.
For sales, it's pointless to know what a customer is interested in if you don't know when they're interested in it, which means you're always better off targeting content over people because content has both temporal targeting as well as interest targeting implicitly right, while person profiling and social media presentation only gets a generic long term interest profile and implicitly targets people doing something other than being interested in products.