Good post. It changed my mind.Assume the AI considers 8 Wpt for a resource a fair trade. Team A can get 1 Wpt and Team B can get 7 Wpt. How is that either fair to the AIs or more importantly fair to the Team A and Team B? So, is it really better to just take what the AI first offers? By offering a subsidy, every Team can potentially get the 8 Wpt that the AIs considers a fair trade. The cost is the 1-7 Wpt in subsidies for 10t. Also there is a risk it won't even work.
Offering a substidy is simply intelligent play. There is no exploit. There is nothing wrong with maximizing your return on every game mechanic, unless that return exceeds the design limit. Assume again that the AI considers 8 Wpt for an ordinary resource like Corn a fair trade. Getting 1-8 Wpt for such a resource is therefore fair from the AIs perspective. However, if we were able to get 9-99 Wpt or more for an ordinary resource that would exceed what the AI considers fair and that would an exploit. Even getting just 9 Wpt would be an exploit. The maximum this technique can provide in this example is 8 Wpt which the AI considers fair, thus there is no exploit.
Sun Tzu Wu
So, if we look at it that the AIs don't intelligently use their slider, so as to have wealth available for trade; or that the code limiting their Wpt offer to their existing positive cash flow - then this technique is just helping the AI make a fair trade for our resource, given how the game decides how to make trades.
Spoiler :
It seems a little tedious and less fun; but not much more so than other micro.