WHO report on danger of drinking RO water

I always put the idea of drinking water without minerals causing harm and up there with cow magnets. Particularly when looking at some of the products touting their solution. However, I ran across this report from the World Health Organization. It says drinking and cooking with demineralized water is bad for you. Can be quite bad.

http://www.who.int/water_sanitation_health/dwq/nutdemineralized.pdf

Oh yes, I have known that for a long time. Which is why I do not drink battery water.

But the million dollar question I have never found the answer to is why do manufacturers of electric irons say quite explicitly that you should not used distilled water in their steam irons, when I have done so for years quite successfully to avoid them furring up?

My guess is that distilled water is quite aggressive and may erode the insides of the iron.