It was related to the general problem of large late-game mechanoid threats almost entirely obviating the need for players to have any economy at all, with the added problem that harder difficulty settings were in many ways easier because you got more resource deliveries from bigger raids. Economy was completely broken, and difficulties were inverted.
I'd like to add my 2 cents here about the problem I see with the late-game economy. Growing psychoid to make flake is incredibly easy once the initial struggles related to your biome have been solved, (getting greenhouses or hydroponics set up if you have a short growing season) and in the late game I usually have stacks of 400-600 flake sitting around at any given time just waiting for a trade ship to come take it off my hands. I could make a caravan to sell off the excess, but usually that feels like too much of a hassle when I can just wait for some to come to me.
On the other hand, when ...
There will always be excessive wealth in late-game at a certain point, that's just the nature of how capital works. We can't involuntarily trash peoples' wealth. The game will always break down past a certain point. I have solutions to this but they're kind of involved (and in consideration).
This was more about alleviating the problem to some degree, not solving it entirely. E.g. You might have tons of flake, but converting that to other usable materials may be tricky. Versus getting massive straight deliveries of plasteel and steel and components - hyper-practical resources.