"stagflation" is simply what happens when inflation keeps up with deflationary trends. It doesn't mean monetary policy is doing nothing. It likely means it's working as intended.
> Japan has had serious struggles fighting off deflation
But the CPI in Japan hasn't gone down, if anything it's gone up more years than it's gone down. Moreover, in what way is Japan terrible? Due to less inflation, there's less income inequality. Maybe deflation isn't bad.
In an inflationary economy, people spend their money quickly, since it's worth less sitting around. In a deflationary economy people hoard cash because the value of cash just increases in the bank. Why invest in anything (companies, labor, capital investment) if your money just earns 10% in the bank?
If enough people do that jobs disappear, as they realize they don't need to market any new product or service to make their money.
FWIW, they call that period in Japan "The Lost Decade(s)" https://en.m.wikipedia.org/wiki/Lost_Decades_(Japan)
Austrians and the HN community talk past each other because it's not easy to get the latter (which I am a part of) to see that their large salaries in FAANG companies are partly due to the Fed largesse.