xXHoax ,

This article is from one the most famous Russian grammar resources. I am sure this resource is under development by professional linguists, so the style of this and other explanations there is scientific and full of exact linguistic terms and definitions.

That article deals with the concrete problem, i.e. use of кушать / есть.

It's better to use есть , which is neutral. This word means just to have food in any situation.

Кушать is used in one of the cases in the context when kids eat.

But most of the native Russian speakers are not aware of that, and use these two words interchangably which is stylistically incorrect according to that article.