There are many people with a medical degree practicing it. UK's NHS supports it. Holy water is much cheaper than the drug industry's offerings. It's a placebo or alternative treatment for a lot of light ailments. Just like folk remedies, most of the time it "works" and you come out alive and well so it's not hard to believe.

Of course it's offensive to science on ideological grounds.

And if someone were to recommend it for a definite diagnosis of cancer that would be irresponsible.

As for Steve Jobs, rationality was not his key to success.