It seem more likely to me that deflation, assuming there really is any, is a symptom.
Assuming the sky is blue, no shit. Inflation and deflation aren't spontaneous, they are results of changes in the money supply and/or the velocity of money. Money supply increases due to Keynesian economics employed by governments is not equal to some bad word known as "inflation", it is a cause of inflation--a cause that has very intended side effects which we all know and love [/sarcasm]. Conflating Keynesian economics with money supply increases is mostly a red herring, as there is nothing that says there can't be a decentralized currency employing some method of money supply increases which would,
no doubt, act magnificently different from government/bank manipulation of the money supply.
It is therefore not an honest line of argument to compare bitcoin to government money. An inflationary, decentralized cryptocurrency can be just as Austrian as bitcoin, and then all of your pro-deflation arguments based on a lack of meddling hold little water. Deflation does not equal Austrian and inflation does not equal Keynesian--these are gross oversimplifications.
The current discussion is in the context of bitcoin's limited supply being bad. When the subsidy stops, bitcoin supply growth will turn very slightly negative. The current, and often repeated, claim is that when inflation stops and turns negative, we go into a death spiral, and bitcoin will fail for that reason. I see no real reason to come to that conclusion, and I'm refuting those claims. I have no particular desire to get into a discussion about whether inflation is the money printing itself, or the money that is printed. But don't let me stop you...
For example of what I'm arguing against:
Again, I'm skeptical of claims that deflation is causing harm in Japan. It seem more likely to me that deflation, assuming there really is any, is a symptom.
Yes, it did and is still a problem there. 2001 was the second worst year in post-war Japan with more than 19,000 companies going bankrupt whose liabilities were 10 million yen or more (an increase of 1.9 percent from the previous year and the largest number since 1984), the real situation being even worse as small business bankruptcies were not accounted for at all. In 2002 Masaura Hayami, then a Bank of Japan governor, said he expected that the Japanese economy would remain in a severe state as prices continued to fall and preventing the economy from falling into a deflationary spiral would pose a significant challenge...
If deflation didn't cause harm and was not at the root of Japan's problems, then what was the cause and why then the government and Bank of Japan took to an expansionary monetary policy in the first place? As with anything, you can always claim deflation is only a symptom and there are some underlying causes hidden somewhere beneath, but does it actually makes things better or render them more clear?
This is circular. The Bank of Japan asserts that deflation is bad and must be stopped, so they print money. Their statements and actions do not constitute an argument in favor of their claim. They had a lost decade between 1990 and 2001, then they started intervention. Now they've had a second lost decade, and are looking at a third. The claim is, of course, that they didn't meddle enough the first time.
Modern economic theory is that all problems are caused by a lack of meddling. If the people that know better than you can't or don't meddle in the markets, we have a crash. And when we have a crash anyway, the problem is always that they didn't meddle enough.