I think it is a bad decision from Facebook to go after Social Fixer. From the Chrome extensions page they have ~200K installs. This is peanuts compared to Facebook's user base(compared to Google where number of Adblock installs are ~40 million combining Firefox and Chrome, it hurts Google more they can't say much about it because of fearing of criticism from their core supporters). But future will be bright for them because people are accessing Facebook more from mobile devices where default mobile browsers are very restrictive and the trend will not change for foreseeable future.