My Greater Sabretooth was the tank and melee DPS, I was the ranged DPS and “healer” with Commanding Presence perk. And we both had self-sustain.
Well-balanced team let’s go!!! 
Nah you’re right, PvE is blatantly easy no matter your playstyle. The exception is “I will facetank all damage” but I’m not sure that can be called a playstyle