After level 84 (I think, somewhere around there) you no longer produce surplus food, which means you have to pay for it to be brought in by Bulkfreighter, or when you get to 0 stored your planet starts to buy it. Also, after level 70ish, you lose 300 people a day which means less steel. The only positive is that your rare resource production (and consumer goods, I think) shoots up, but after a while you just can't spend it all.
This.
The optimal society level for production on most planets, IMHO, is about 70-75. More than that and you're losing so much steel and hydrocarbon production that rising production of antimatter/krellmetal/whatever seems pointless. And the graph makes it seem like Quatloo production may slow down as well, but I'm not sure.
If you MC your planets and then set up fixed trade routes with BFs with a few select planets having all the upgrades and most of the cash, it should lead to a relative centering of resources on those planets.
