[akjssdk]

True, but at least it prevents them from linking accounts. It is equivalent to no profile picture, which you might not want to keep up appearances.

[zgramana]

You may be surprised to learn that your face is your least identifying trait online. You network of friends/followers/likes identifies you far more readily—even if you use a random username.[1]

Managing your privacy is a lot like CPU side channel attacks. It forces you to re-evaluate your fundamental assumptions about what information can be exploited.

[1] http://www.vldb.org/pvldb/vol7/p377-korula.pdf