You're not answering the question though. Would you be okay with the idea if it ends up redistributing existing coal from refineries onto the map, instead of a flat increase? And if not, why?
Because right now, you're ultimately just arguing for the status quo here, and I'm not sure how your argument of "resources should be limited" applies.
I specifically amswer by stating that resoyrces should be limited and players should have very strong incentive to fight or at least to make a strong competition case for them.
For instance, if you play on some "Pangea plus" map and you find yourself in a predicament when there is only 1 source of coal on your territory you will have incentive:
a) to search for coal resources in other territories (including uncharted ones) and found cities there which in turn urge you to think about how, where and when carry on expeditions, where to found cities, how to develope those cities, which army you need to deploy in those newly founded cities, how to connect those newly founded cities with your capital etc.
b) to look for your rival territory and realize that your neighbor got 10 (!) sources of coal and whats the best thing - that neighbor does not even know yet about that since no required technology being discovered. Over thorough consideration you are eager to start a short war in order to capture 2 cities with rich coal sources around them.
c) to peruse your territory and your closest neighbor territory and realize that you are both so unlucky of having only 1 source of coal. Then you will search for coal elswhere and realize that in very distant lands Inca got embarrassement of riches and monopoly on coal. The problem is that Inca been so far away from you all that time you have not even cared to interact with them. But now you have a very strong incentive to make deals with them, which in turn might require Declaration of Friendship, and you might want to reach that agreement before your poor closest neighbor does. But wait, if you reach that DoF with inca, that might infuriate your poor closest neighbor and he could attack you.... hm.....
There are also d's, e's, f's and other incentives in this scenario. But, all those incentives suddenly disappear when you got 20 coal sources and all you have to do is click on your worker to build a mine. I think, you got the point.
Regarding refineries: there is a reason you can build a limited amount of those in your empire and you might need to build them in case you have shortage of coal but that coal you get from refineries shold meet only your basic requirements, for a much better life you might want to resort to those incentives a just listed above.