You’re a fb employee. You work at a company that has, as its sole purpose and function, to harvest as much information from as many people as possible, with or without their knowledge and with or without their consent.

Also, smart employees doubt the confidentiality of these surveys. Management almost always gets obsessed with loading these up with all kinds of granular information about departments where respondants work, age, length of service, gender, etc. which makes it easy for bosses to start guessing who the complainers are.