This isn’t a ridiculous situation at all, but instead makes things individual and different, as opposed to when it was different, where you could blindly go for production increase, since it would always pay.
It’s not all or nothing, you know. Lots of games have spillover existing but penalized. I have no opinion on whether gameplay is better with or without production (and research) spillover. What is obvious, is that the lack thereof is a huge newbie trap. Clearly, veterans gain a lot of comparative advantage from this, and I’m hoping resistance doesn’t flow from this. For myself, as I come closer to figuring it out, my interest in changing things is declining.
If, for instance, there is spillover but half is lost, there is still room for optimization by veterans, but newbies aren’t so heavily punished.