Actually...When it was first marketed, it was mostly cheese. The point was to extend the 'shelf life' of a cheese product. His first customers were the US armed forces. Packaged food that resisted spoilage. 'Processed' cheese...processed to make it last.
In the world of fast, convenient foods, much has transpired since the introduction of Cheese Whiz. It is not the same thing any more.
I was mostly amused to find that it was developed to address the Welsh rarebit market in the UK and only introduced in the US markets as an afterthought.