I was going to say not practical for long-term survival, due to the relatively large costs of the jars and then the storage space required, but you’re really looking at it for non-refrigerated short-term storage of excess food. That does make sense.
Depending on the items stored they can last anywhere from 3-15 years when stored like this. Most of my jars have been purshaed on sale, at yard sales and closeout sales. Storage space includes closets, under the beds, under couches, and in my pantry - generally areas not used for anything else.