My argument against the “extra weapons” theory is that Rogue also has extra weapons, but has never performed directly below Barb and above Necro/Sorc/Druid in S1-S3. So that right there shoots that thesis in the foot. The only reason for Rogue S4 performance is due to Heartseeker, and I still wouldn’t put that above Necro.
The issue with Barb has never been the extra weapons; it’s all the multipliers through stacking skills/paragon. It’s also exactly why those multipliers are now starting to get capped.