Even with full STR, the best tank in the game isn't doing the same damage as a DPS unless the DPS is bad. A full STR tank can do about 75-80% of a DPS's DPS if both are going full HAM.
I'm i197 Summoner, and my friend i203 WAR, in dps stance, can do as much as me single target in Fractal (900-1000 dps on bosses). Sure on aoe they lose out (do 600 to my 2200), and Summoner isn't that great single target, but yeah WAR can still 'replace' a Summoner in fights where Summoner isn't aoeing. Haven't seen a Scholar pushing 1000 dps yet.