Years ago, I had a pizza stone for the oven. Like other things, it disappeared when my daughter got her own place. I looked for a long time for a used one on Craigslist. I could have bought a new one for a price, but I decided to find one for less on CL. After looking for a while, one finally came up on CL for around $12. It now lives in my oven. Whenever I heat up my oven, it gets heated up. It works well to set a baking pan on such as when I am heating up chicken or other things.
But, I have long thought that in a grid down or SHTF situation, an outdoor pizza type oven would be a great thing to have. There are YouTube videos and other instructions to make them online. I want one, but haven't built one. I think they could be built by any of us. I also think it is a good idea for cooking in the heat of the summer.
I was thinking of a roommate I had who was from Morocco. She told me that they had big ovens in their neighborhoods where you could take your stone dish with food in it and leave it to cook. I think in places where it is really hot, like Morocco, a central oven, outside of the home is a good idea, as long as there are not people who abuse it.