Why is the healer class basically a one spell dps class?

[Semirhage]

We had close to that in SHB launch. Healers were in extremely short supply.

Oh that's because there was a new tank, you see. Nothing to do with terrible healer design or anyone quitting. Healers dropping the role? Preposterous. Low-skilled Sylphies and AFK Netflixing DPS moonlighters replacing the ones sick of it? Trick of the light. Not happening.