"I heard"

The beginning of many a mishap!

What about the water? Distilled water is "hungry" water and will dissolve a lot of things. So if you had some mineral buildup in a radiator and were going to run ONLY water, distilled water may actually clean things up a little.
If you have a brand new system, running ONLY distilled water will liberate some ions from the surfaces but isn't going to eat holes in engine or radiator. It would be okay.
There are other things going on, however, so the preferred way to do things would be to use distilled water and either anti-freeze or some other corrosion inhibitor/water pump lube additive.

It is far from complicated science. It is easy to get OCD about fluids in automobiles, all this will do is get you to the psychiatrist faster. Then hopefully, she'll prescribe some good drugs and you can go back to filling the radiator with the garden hose, checking the antifreee content in the Fall, and getting on with your life!

R. (happily medicated)