During the lost era where physical trade was the economy, precious metals represented physical value.

No one is measuring knowledge value in units of precious metals.

Gold simply does not back anything any more because it no longer correlates to the intangible knowledge that is valuable in an era where knowledge moves the economy.

Back your lost era, knowledge was less important than land ownership, number of head of cattle, etc..

Also we are in era where digital reach is ubiquitous geographically, thus there is no place to hide from the fact that governments want to be able to tax and physical gold as untraceable cash would prevent them from doing so. Thus governments will fight gold as cash and besides for the reasons I stated above, gold is not a representation of value any more in the knowledge age.

Gold is hanging on because the physical industrial age is not quite dead yet. But gold is fading fast.

The physical economy is fading away in relative value (relative to knowledge creation value). It won't too long from now that physically manufactured items will be nearly free.