While this is generally true, land values do tend to rise over time simply because the population increases and thus there are more people competing for a finite resource. It's a value change that can only be measured accurately over decades, however.
Indeed; although there is a historic counter argument to my point. Not so long ago land was such an important economic asset and it was concentrated in so few hands that those who owned any could easily live off their ownership for generations and even accumulate more wealth in the process, while everyone else was doing the actual labor. It was called the feudalism. And that is precisely what a deflationary currency would result in.