The distinction might be petty, but for even a junkie, used might be a more accurate descriptor than user. As a non-junkie and non-member of the criminal infra

The distinction might be petty, but for even a junkie, used might be a more accurate descriptor than user. As a non-junkie and non-member of the criminal infrastructure, one might see "drug users" feel used more than empowered through their gain of utility. Same is true for facebook "users" as well. If you see "user" as someone who uses a product, then this discourse is pointless. But if you think of a "user" as someone empowered by products, then using the term "Facebook users" should make you feel uncomfortable.