Well, I suppose therein lies some of the perception problem.
SR75-80 should never be “without much sweat”, whereas SR60-65 should be a challenge. In your example, your Malakor build would be in a comfortable range and the Warlord would be overperforming. However there is never going to be a perfect distribution of builds across SR/Crucible/Super Bosses, so SR55-75 is generally the ideal of a godly endgame SR build.
That said, I am curious to see how far people push when we add the Deathly Waystones that can go forever (without rewards). They might be more of an MP thing though. 