Polearms are DEX based weapons.
No they are not.
I have never opted to play a monk or use polearms as I find both incredibly dull and boring concepts but generally I have seen monks use polearms more than any other class and Monks are a class that primarily depends on DEX and WIS builds. Why would they use strength weapons?
Are you mayhap mixing up polearms and staffs?
Not that I was aware of staffs being DEX weapons ...