Why would we want to though, when it keeps us in a Gilded Age and burns Stability? Six Wealth in return for three Econ and one Stability is a cheap price to pay at this point.
I'd happily pay six Wealth for the Stability given it costs no actions.
We don't save 3 Econ for switching away from paying Mercenaries directly; direct payments cost nothing, other than the Martial tolerance they temporarily consume.
So what you are actually doing is paying 6 Wealth in return for 1 Stability.
Except that isn't what you are doing. Gilded Ages also give us Wealth, which means we are giving up another 3 Wealth of lost income, and more if we reactivate any cities. So now you are trading 9 Wealth for 1 Stability. That sounds like a pretty expensive Stability point.
But wait, there is more! In addition to the 9 Wealth you are giving up, you also lose the ability to take whatever GA purchases might be on offer. Such offers have traditionally included the following:
- Megaproject Track (6~10 resources)
- Value Slot/Upgrade (10 resources)
- Hero (12 Resources)
Now, such purchases are very often worth taking, so that is providing significant value by itself. However, so as not to make the argument too abstract, lets imagine we bought only a single innovation, with the 9 Wealth we saved.
The result is that we are trading a single point of stability and a point or three of additional resources for an MP track, or a Value Slot, or an Value Upgrade, or a Hero unit. That seems like an extremely favorable trade.