Also, it might be expected for technological change to happen extremely slowly when you have such disconnected states and small communities. He recognizes there

Also, it might be expected for technological change to happen extremely slowly when you have such disconnected states and small communities. He recognizes there are very poor transport and communication networks. How exactly would he expect information to flourish and where would he expect innovation to come from? I think in the real world, the hunter-gatherer culture lasted about 2 million years. Obviously middle-earth isn't hunter-gatherer but its some point of reference. From some very quick searching it seems like the start of agrarian society through the middle ages was about 6000 years. And again, as the author notes, there was a much high population density and network of people in the europe/middle east/western asia in the real world. The 12000 years without significant technological advancement seems entirely plausible even in real terms.