1) People still can't feed themselves and go homeless, countries that have inflationary policy sill generally have well developed welfare policy. It also isn't obvious that purposefully increasing the price of food and housing is helping, the bar of evidence for such an unintuitive claim is higher than "it's just obvious, trust me".
2) There was a different monetary system in the early 1900s. The lessons learned about it might not apply to a fiat system. Lending, credit & and the nature of money all work differently now.
3) If the problem was wild swings, then the lessons to be learned were in how to moderate the booms. There needs to be a bit more explanation about how increasing the money supply does that, and whether it dampens the booms more than it helps the busts. Smoothing the cycle is a mistake if it lowers trend growth.
4) Lack of evidence cited. "we discovered" is handwaving the important part. I suspect that is like "discovering" means in the political sense where politicians lie about something obvious as cover for a policy that they want.
5) Ignoring technological innovation and all the oil that has been used over the last 100 years. It is likely that the dramatic reduction in human suffering is totally unrelated to inflation policy.
