No, it really is the PvP. I recall the "epic battles" (and insults, so many insults) I got thrown about with by PvP players when complaining about armor in EA.
And no one listening that what works for 10m PvP matches might not do so in a 100H SP-game.
It's probably a bad system for PVP actually. As I explained, if both teams are equal on everything else, a skewed team has some inherent advantage over a balanced team, and depend on makeups, a skewed team can counters another skewed team. So PVP outcome is significantly influenced by pre-game decisions on armors and damage types.