Except it's just marketing. Most rust removal products are formulated with acid as the active ingredient and are not pH neutral.What does the pH value mean for cleaning products? - Cartec World
The pH value plays an important role in the effective removal of dirt or deposits. It is different for each situation when you should choose an acid, neutral or alkaline product. Do you know when to choose which cleaning product?cartecworld.com
The key thing is, you are only writing "iron" when this topic is about iron that has turned to a rust stain, as it always does if not removed immediately. Even the page you linked, states acidic pH for rust. Did you think all those manufacturers who use a acid as the active ingredient, never bothered to test their products and just did it on a whim?