In any modern, first-world country, the government requires legitimate university researchers to go through an independent review board (IRB) when conducting research on human beings. This is due to past abuses by both governments and organizations who have used the guise of “seeking knowledge” to cover up their efforts to manipulate people for their own means and ends.
But you know what? Facebook isn’t a first-world country. So in an effort to better understand how to best monetize your use of their service, they don’t need an IRB’s approval to conduct research on you.
And now, in my opinion, they are outright mocking their users with their latest update to their research practices.