Uh? I'm guessing you're referring to WHM and Noct AST? If so, a correction here:
WHM+Noct AST was the goto out of the gate, eg: world first Deltascape clear. WHM also saw plenty of use in Sigmascape as an FYI. By Omegascape, WHM's scaling and mobility woes had caught up with it and it was indeed getting out performed by AST+SCH for sure. I distinctly remember Hello World being significantly easier on AST as well?
Overall though, I'd say that SB's healer balance was still better than HW at the peak of the end game. 3.0 AST was massively worse than anything else we've experienced since, 4.0 SCH included, meanwhile 3.4 WHM was in a bad enough state that it literally had to stand there doing nothing at times to have enough MP for A12S. 4.4 WHM wasn't optimal, but again, it wasn't anyway near as problematic.