Moderate deflation is fine, it's good even. But only as long as nominal GDP stays stable.

See the so called 'Long Depression' in the 19th century. Which was only a depression of the price level, everything else did well.

For a more sectoral example, see how computer hardware used to get cheaper and cheaper all the time, but total spending on hardware went up.

That is https://en.wikipedia.org/wiki/Jevons_paradox