These kinds of statements are not productive and are entirely inaccurate. Plenty of Sorcs do excellent damage in PvP.
I concur. However, for my DPS Sorcerer to truly be effective and do the kind of damage other ACs are doing, I had to spec 20/21
(Lightning/Madness). Though, that shouldn't be the case in my opinion. With this build I finally broke the 400k mark and do so a number of occasions that is when I'm in a protracted battle.