What are you smoking?  Priests make great healers and great single target DPSers, but they're lacking in two key areas: crowd control, and tanking.  Sure, we have silence and shackle undead, but those are situationally useful, where as a Hunter, Mage, Rogue have CC that is much more usable.  Second, we have NO armor.  Even if you were in shadow form, wearing lots of stam and pvp gear, a priest would still get owned easily in almost any instance he doesn't have well out-leveled.

Druids could pull this off, Paladins too, and maybe Shamans, but you can forget about a group of priests pulling it off.

I guess your right cause priest are realy for backup, revival and protection, how ever..priest can do great damage and shield themselves and they have at level 30 and up the spell to control minds. That power is best for having time to run away and make enemies fight each other and kill themselves. My point is that priest are powerful and good, they just need alot of mana...but your right a team of priest would be a bad idea and since they cant handle as muct damage as the other classes.