That is not optimizing healing,
YES, it IS. It's not optimizing DAMAGE. Which is my point - optimizing healing and optimizing damage are two distinct things. While the first is a means to an end if your end is the second, the first can exist in vacuum without the second, proving they are distinct.

I don't even know where to go with rebuttals at this point.

You're trying to argue a "but technically..." while not even getting it correct. You seem to very much want to win the argument, but the problem is, the argument isn't even relevant to the discussion.

At best, in some hypothetical encounter where the healer's damage has insignificant impact on the fight duration, your counterpoint is a mere excuse to do the bare minimum of the healing role while sitting on your thumbs.
Welcome to the joint strawman ad hominem fallacy.

Where did I advocate for people to optimize healing and then do nothing else?

I was pointing out one COULD do this to prove to you that optimizing healing IS DISTINCT FROM optimizing damage.

Instead of recognizing the point - and that it proves your technicality wrong - you chose to attack me for an argument you invented me making that I never made. I never argued anyone SHOULD play that way. I argued that by fact a person COULD, it proves optimizing healing is not optimizing damage, it's just an additional requirement if one DOES want to optimize damage, but is a distinct action that can exist without it.

Shadows cannot exist without a light source, but in vacuum, light sources can exist without shadows.

In reality however, what you're actually doing is drawing out the encounter -- "sandbagging" the team -- thereby creating a self-defeating point as you will require more healing overall due to the extended fight duration. And this is without taking enrage mechanics and DPS checks into consideration, where your failure to optimize damage kills everyone.
This would be an AMAZINGLY good response...if I was actually advocating for a course of action.

Can you show me where I'm doing that?