The Empire cranked out the worthless currency during hard times and increasing debt—Keynesian theory didn't begin with Keynes--some Roman economists thinking they could spend their way out of downturns was a big part of the decline.
Historical value only.
Quite the reverse — the Roman economy boomed because the Romans figured out that currency is a gov’t defined medium of exchange. Had they not discovered this, the Roman Empire would have vanished during the political chaos of the 3rd century. From the standpoint of having a pile of gold, the Roman Empire peaked under Trajan, but economically it thrived when the tax-crazy central authority was pretty much off everyone’s backs and local or provincial authority was busy fighting the neighbors.