Using BTC as the unit of accounting is the same as using any other stable thing as a unit of measure. For instance, an ounce of gold is an ounce of gold now, before and forever! The same with an ounce of silver. In terms of an ounce of gold you could by a nice bespoke suit and all the accoutrements, right now. In the times of the Roman Empire an ounce of gold could by the nicely tailored toga and all the accoutrements. What you could get now and what you could get then are the same in terms of a stable commodity. BTC is a stable commodity, whereas fiat is a diminishing promise.