Many were held up by a brace that could be removed when the chimney caught on fire allowing it to fall away from the house.
This made me chuckle but hey that's pretty good thinking. If thats all the material they had at the time it would save their house from burning. Disposable chimneys!
But I've learned a lot in this thread I'm glad I brought it up. I really do see a lot of these sided chimneys matching the house and now I know it's capable of supporting really any burning appliance. They are still ugly as sin though. If I ever move again (only way thats happening is if I somehow come into millions lol...I hate moving) and I cant have bricks I'll go brick or stone veneer for the aesthetics.