I like the way you used moderate. There is a reason that you did, and I think that is one of the reasons that bitcoin is thriving.
But we have moderate inflation in most countries so I do not see you point.
We do have moderate to low CPI inflation in western countries, but we also have high inequality and a young generation that doesn't have any assets. Now, if whether you call that inflation or not, the reality of the matter is that the cheap money situation we are in has led to this situation where we have rampant speculation in stocks, real-estate, crypto assets and any other form of limited supply assets. So I think Bitcoin and the crypto asset class, is here to stay, offering its own unique set of advantages and disadvantages.
CPI is a cooked up government statistic, used in contracts and agreements (including social security) that unconditionally favors the governments position. For example it does not include energy or housing costs.
They also add and remove items from the CPI index, to remove ones that inflate and add ones such as consumer electronics that deflate.
Check out the chapwood index or a different unbiased inflation metric.
Fiat currency also has the nice property of being able to be used as money (payment for goods and services). So no, a well managed fiat currency can be extremely useful.