The article doesn't discuss the differences among sex crimes, or the levels of sex offenders on the registry. Judges ban people from the internet for lots of reasons, generally on the basis that the use of the internet has some connection with the offense of conviction (or alleged offense, if pre-conviction). It's not unusual for a condition of pre-trial release for a fraud involving the internet to be no computer access at all -- to the extent of cutting off internet access for the residence if you're out on bail. A post-conviction ban on internet access, especially chat-site or social media access, makes sense if the crime of conviction involves online predatory behavior (whether sexual or otherwise), and I would certainly ask for that at sentencing, just as I would ask for mandatory AA/NA counseling for a drug defendant with addiction issues.
A full out ban on social media access without regard to the nature of the sex offense make very little sense.