That is true. Whenever I see these designs I feel like I would like to develop a hybrid model - to use with either solar heat or other heat sources when needed.

Or for a low low tech solution, a drying rack that can handle a fire under it. Things will be smoked rather than dried, but that's not necessarily a disadvantage.

Yes, but first I have to build a few and test them - they are result of a few years experimenting and thinking about the problem from the perspectives of ease of building and using it, repairability, flexibility, price ... It has the option to stack frames as high as practical and cover a stack of frames with either mosquito/flynet or shading fabric or a combination of both, and add any heat source to the bottom of a stack. The current heat would be great for drying all sorts of stuff and put this to the test, but unfortunately the same heat is crap for any mental and physical activities, so this project has been progressing slowly. But it is one of the parts of my small gardening and processing cycle. Equally slow is my documentation of this cycle. I'll try to come up with a drawing of this idea!

It is deliberately inefficient and wasteful. Just trying to point out the physics. Do what you want, inefficiency can be enjoyable. You should just temper your expectations to effectiveness and convenience.