“if there is no income inflation isn’t the relative value of the currency still held?”

relative to what? if not goods (and the cost to purchase them), what else do you do with it?

what if you’re the farmer and you pay your workers 1000/mo. they in turn have to buy their food from you. what prevents you from simply charging them more? especially if you’re the only game in town? you have price inflation without wage inflation or monetary inflation…