Yeah it's a pretty self-absorbed thing to do (and say).
Like, there's no harm if the outcome is mutually beneficial... but you just have to know deep down that posting one picture of a beach out front of a resort for your 2,000 followers to see is not going to generate a worthwhile amount of interest in the resort in reality... But I think most "influencers" are completely deluded anyways, so maybe they really do believe that posting a couple vacation photos is of equivalent worth to the vacation itself...
It's like people who approach photographers and request that they work for free to "build their portfolio".