Ehm while I disagree with the practice it feels like standard protocol at the intersection when successfull start-up becomes a business. To single FB out then seems out of place.
What I see from startups are adding new premium features to pay for. I can't recall a successful startup that's done a bait and switch like FB. I'm genuinely interested in a few examples (I'm sure there are plenty, I just can't think of any off the top of my head).