The Wall Street Journal has published the article where its staff blames Facebook for tracking the audience activities of competitors, including Snapchat and Periscope. The author refers to his own sources.
A special analytical service assists Facebook to optimize current features and take important product solutions.
This special service is Onavo, which was acquired by Mark Zuckerberg in 2013. The company develops the app for data protection known as Onavo Project.
Onavo Project redirects traffic to Facebook server systems when Onavo users open a site or any application. After that, Facebook developers can analyze the information received. They get the information on how users post and like, the number of users by country, the gender and age ratio, etc.
It seems that Facebook analytical service was used to develop the strategy of promoting live broadcasts on Facebook and Stories on Instagram.