> spinning wheel (which should have been invented 1000 years before it did if inventors thought about it at all)
Nope. You can invent it, but if there is no economics to drive its adoption it won't spread.
Medieval thread production and thread consumption was roughly balanced so there was no great economic incentive to engineer it.
A spinning wheel is significant labor from a craftsman which means you need to have excess cash to buy and maintain it--farmers surely didn't have that. In addition, if you suddenly generate 10x the amount of thread, that doesn't mean that it can be consumed--weaving doesn't magically get faster. There isn't a lot of trade beyond a single village, so there is nowhere for excess thread to go in order to become money. All this is even before you have engineering limitations--spinning wheels didn't create great thread for weaving from most fibres.
(Side note: In fact, the excess thread from spinning wheels basically didn't get consumed initially. It just created a surplus of rags. Which then led to printing because there was suddenly a cheap supply of something looking for a usage to consume it all ...)
Contrast this to later: The invention of the flying shuttle suddenly kicked up demand for thread which then needed the spinning jenny which then needed the cotton gin. That was all "demand pull"--there was pent up demand that would result in profit if you could fill it. And, even still, a LOT of "inventors" went bankrupt inventing all those things!
I think you are completely right about demand pull being a deciding factor in adoption of new inventions. Many question why Rome never entered the industrial revolution, especially considering that they invented a steam engine[0].
Although I would question if multiple hours of daily labor isn't itself a significant demand pull? I assume everyone wants to free up time spent on monotonous tasks, but maybe this is wrong.
The Aeolipile was not a functional steam engine - it was essentially an unpressurised two-spouted kettle that span on an axle. It had no way of maintaining enough pressure (no valves) to do useful work and the metal working techniques of the day weren't good enough to contain useful pressure without exploding. Real steam engines only came about after people had spent centuries building cannons that didn't explode.
The first practical application of steam engines was pumping water out of deep coal mines (which the Romans didn't have or need) where it didn't matter if the engine was both underpowered and massive. Even after these engines became commercially viable, it took another 70 years or so for the engines to become small enough to be mounted on vehicles.
There was this synergistic interaction between coal and iron ore deposits, trains and the steam engine. Having a portable steam engine meant that you could build trains, which meant that you could transport coal and iron ore to the steel mills, which meant you could build more steam engines, which meant that you could build more trains and expand the rail network. The fact that these things followed one another wasn't a coincidence.
Nope. You can invent it, but if there is no economics to drive its adoption it won't spread.
Medieval thread production and thread consumption was roughly balanced so there was no great economic incentive to engineer it.
A spinning wheel is significant labor from a craftsman which means you need to have excess cash to buy and maintain it--farmers surely didn't have that. In addition, if you suddenly generate 10x the amount of thread, that doesn't mean that it can be consumed--weaving doesn't magically get faster. There isn't a lot of trade beyond a single village, so there is nowhere for excess thread to go in order to become money. All this is even before you have engineering limitations--spinning wheels didn't create great thread for weaving from most fibres.
(Side note: In fact, the excess thread from spinning wheels basically didn't get consumed initially. It just created a surplus of rags. Which then led to printing because there was suddenly a cheap supply of something looking for a usage to consume it all ...)
Contrast this to later: The invention of the flying shuttle suddenly kicked up demand for thread which then needed the spinning jenny which then needed the cotton gin. That was all "demand pull"--there was pent up demand that would result in profit if you could fill it. And, even still, a LOT of "inventors" went bankrupt inventing all those things!