I think is validity to the argument that capitalism as a system built on private debts should avoid deflation. True, from the worker's perspective it appears as if the prices are getting cheaper under deflation, but is that the case in the aggregate in the long term? Are capitalists laying off workers because debt servicing is more difficult? Does it discourage future investments? Will the state take over to create employment that's been lost?
In that sense, true price flexibility downwards can only happen in a centrally planned or heavily state interventionist economy as the state isn't financially constrained in the way private entities are. Under capitalism, it's best to have money wages rise than have the prices fall. But neither is happening in the West.