This is spot on. It's just like any other marketing tactic - it works well until everyone else starts doing it.

As for the pricing of posts, the lowballing is getting more and more dramatic, because there are many more "influencers" now. The only brands really shelling out are large corporations with large budgets looking for something very specific. Smaller brands can just reach out to a bunch of influencers offering only product in exchange for a post, and someone will say yes.