Industrialization is a half urban half rural phenomenon, since industries depend on raw materials created in the countryside. What I was saying is that classical economic theory and marxist theory are both two sides of the same coin and largely wrong in their assumption that some kind of surplus in something leads people to use the surplus resources to create something else. If something is doing so right that it is creating surpluses, chances are that you're not going to want to abandon this activity. There is no one-scale-fits all, no grand historical narrative like marxists like to try to build. Urbanization happened in different places for different reasons, material dialectics is at best capable of explaining process of urbanization and industrialization in north europe during the enlightened period, but even there will be people contesting this.
Muslims created the biggest cities of the medieval world, but they were neither rural nor urban people, the people who created those cities were seminomads from the eurasian steppes or the deserts of north africa and middle east. The reason why they created such big cities despite being barely used to sedentary lifestyle has more to do with their religious motivations than any kind of economic surplus.
Greeks kept their polis just for the sake of it, they were used to this lifestyle, this is how they organized their societies and politics, so they had no reason to adopt any other kind of settings, although it could be argued in mere economic terms that it would have been more profitable for them to abandon their cities and adopt a more rural lifestyle, since they didn't have the agricultural surpluses that Egypt had, for example.
There are some theories that say that catholic celibacy was one of the reasons why late medieval euro cities grew so much, because you had these tons of monks and friars (also some nuns) who were highly mobile and not obliged to dedicate themselves to any family or feud, so they moved from city to city where they could study with different people. Which caused the exchange of ideas among euros to increase a lot.
I could just go on, my point here is that there is no grand theory of how people go from farm to cities, like traditional economic theories (including marxism) try to insist.