I am not saying there was any free market capitalism in feudalism. I am trying to explain to you the basic economic principle that those that can produce something more efficiently will tend to dominate. I used the example of corporations under capitalism as an example that I hope you would be more familiar with.

If I need to use 90% of my population just to produce enough food to sustain them, I can only use 10% for other things. The society that only needs 50% of the workforce to be in agriculture can easily entertain for example a vastly bigger military even with the same population.

Economics is what wins war. Economics is what allows technological progress.

Yes, slavery existed but the question is what the dominant form of ding agriculture.