Up until now, wasn't Facebook collecting large quantities of data about users from data brokers? Why were they acquiring that data about users? In the leaked

Up until now, wasn't Facebook collecting large quantities of data about users from data brokers? Why were they acquiring that data about users? In the leaked memo from a Facebook senior executive, what did he mean by "questionable contact importing practices"? Do contacts count as collected data? Why does Facebook collect contacts data, and why does FB collect it in ways that are "questionable"? Why are the contact importing practices questionable?