> Citing an average number is misleading

Not when you are also citing the coefficient of variation it isn’t.

> since the chart of the value of a dollar during that time looks like a zig-zag with some massive swings in both directions.

Uh, exactly the claim made, “we have accepted higher inflation in order to achieve stable inflation that is predictable.” (emphasis added)

Characterizing this as a bad thing is, IMO, quite bonkers, but so is denying that it is exactly what has happened.