@OlivePit Marketplaces would not be limited to residents only. Marketplaces are like the banks, where anyone passing through the city can use them, or at least they were in the last test. And marketplaces being linked also has to be researched. So a lone city researching a marketplace actually hurts themselves by using the point for that rather than something like leatherworking. Just using that as an example. Neighboring people would be able to go to that marketplace to use it, but then they would want to reside elsewhere that has the crafting researched for their own progression.
Mind you, I'm not saying that nobody should research marketplaces, and it does make sense that cities can't unlock everything at once, but the way it's currently set up, marketplaces would not be a big priority for cities to unlock. Maybe something needs to be tweaked there.
