FB and much of the current social marketing scene in general have been handing off best practices that feel highly questionable at best.
Why did you choose to include that bug into your code?
Srsly, people don't choose to make mistakes (but sometimes they choose to do cover up).
Also, there is no such things as "Facebook". Facebook didn't choose, someone inside Facebook either make mistake, or deliberate decision. "Facebook" is not single entity with single agenda and plan, but complex company, with different people optimizing for different things (i.e. security/privacy and growth and ads). There is shared high-level vision, but not every decision is made at single place.
You say it was a mistake, at the same time you give many reasons why it likely wasn't a mistake: many people vet the public-facing communications of such a large company.
As a bonus, it pulls money away from YouTube.
[0] https://www.businessinsider.com/facebook-exaggerating-view-c...
You're understating the monopolistic power that Facebook's network effects have produced in the online content space.
It's only recently that third party analytics companies came into the space with an incentive and enough data to make meaningful market-wide forecasts.
Your comment is still very valid for small clients on self-serve systems, though.