What do you guys think is the cause of severe lack of Tank users?

[LalafellDown]

I've had several tanks get mad when I did this and l've made a post about it before on these forums, in which by far most seem convinced you should never do this as healer because it seems to violate some arbitrary etiquette.

I don’t understand why some of them get angry. I personally love it when healers do this when I tank.