Well yeah purchasing by means of bitcoin has been extremely "deflationary". The price of a pizza (let's say a $10 USD one) has dropped from 10,000 BTC to 0.004 BTC...
We have not had a capped supply fiat currency since the gold standard was abandoned when it was effectively capped due to the finite supply of gold. As fiat currencies continue to inflate as there supply is increased, bitcoin will deflate even more in fiat terms with its 21M coin cap.

It is also sophistry to claim bitcoin "has no intrinsic value"... what is the intrinsic value of any fiat currency that is not backed by any asset class? Fiat currencies are backed by the solvency and integrity of the issuing nation. Since the US has not defaulted on debt (not anyway since the adoption of Hamilton's system after the constitution was ratified) the US has become the world's reserve or "default" currency.