Random aside: Suppose for the sake of argument it was possible to do something like ARR where we split healing as a role into two parts that were...actually functional (unlike the Pure/Barrier split which seems to basically be meaningless outside of WHM/WHM comps since everyone else has barriers anyway...)

Where we had one that was a healing focused set of healers, and the other a support/damage focused set.

The former are designed to have powerful and efficient heals with a slimmed down damage kit while the latter are designed to have a more expansive damage suite and dynamic gameplay shifting between support healing and buffing the party vs optimizing their damage potential.

If there was a way to do this where it wouldn't devolve into a meta of 2x supports (let's pretend this is possible), would that not be an interesting and possibly useful change to satisfy everyone?

I get there are a lot of "That's impossible..." what-ifs. But for the sake of argument, let's pretend. As I noted above, on at least some level, this was how healing in ARR worked, and players were (at the time) largely satisfied with this, with many loving both healers despite their individual focuses. Set aside the "impossible" and "ARR wasn't REALLY like that by 2.4 and on..." and so on, just a thought experiment.