When I was a kid, there were some other kids up the street who loved ketchup & american cheese sandwiches. Mustard could be mixed in if you were in the mood for something a little more upscale & tangy. These same kids also used ketchup for a soup base, if warming up was what you needed on a cold day.
These were the people I immediately thought of when I saw that Ritz’s eating suggestion for their bacon crackers was to use the crackers as bread to make a ritz w/ box mac & cheese sandwich. Yum yum!