Why was that done traditionally? Because if you had a chimney fire, you could hook your mules to it, pull it down, and save the house.

This seems right but I don't know enough about chimneys, mules or even houses to determine if it's true.

c.f. "Little House on the Prairie". Chimney fire is for real.

If we're talking about chimney efficiency then we should talk about including heat exchangers within the chimney walls.

Jamie Hyneman of Mythbusters added one to his house and talks about it here https://www.youtube.com/watch?v=0T3nIk3S8Wc

I was wondering that too. If I wanted to design a wood-burning apparatus that would be efficient and last 1000 years, I'd use a design that was more like a masonry stove (centrally located on the inside of the house). In any future (I think), a backup source of heat in a cold climate is a necessary redundancy? I would use the most efficient tech now for the burn chamber (rocket?), but also design the burn chamber in such a way to allow for it to be replaced with better tech in the future (perhaps the masonry stove outer structure and thermal bank would support itself - steel exoskeleton? - etc.).

It also causes condensation because of rapid smoke cooling. Tar condensate will slowly seep through chimney wall.

Stainless or ceramic chimney liner slows that process down, but neither will last a 100 years let alone a 1000.

Not to mention wood fireplaces in the home and the noxious byproducts they produce is likely to shorten your lifespan considerably.

Bah. Freezing to death in an ice storm can also 'shorten your lifespan considerably'. There's damned good reason to want a simple, off grid means of heating your home if you lose power.

This is not the case when using modern wood burning stoves though right?

Apparently they're not as great as people have been thinking

https://www.theguardian.com/environment/2020/dec/18/wood-bur...

Or wood burning fireplace inserts that draw combustion air from outside and expel the fumes/combustion byproducts outside as well. Not ideal for local air quality, but essentially eliminates indoor pollution from them.

Well sure, if you are the only person for miles that uses a fireplace.

Additionally, I think people who are outdoors still have to breathe air.

To that point -- last summer, my friends moved from a mountain town under constant threat of wildfire to a pleasant spot by a lake in the Midwest -- their new neighbor keeps a fire burning 24/7, so they still get to enjoy the terrible air quality all winter long.

Unless it does turn wood into a pure gas without a trace of sulfur, silica etc. it must emit such stuff. Or it comes with filters cleaning fine particles, nitric oxide etc. In the end it does emit CO2.

Wood pellets largely solve this.

the smoke goes up the chimney.

Most of the smoke goes up the chimney. You still open it to light, relight and sweep away the ash and in that time you're going to breathe in some smoke or dust particles which you ideally shouldn't

Mine's gone out...