I think the phenomenon you're observing is that the quote observes a true correlation, coincidence, or relation, but "sounds crazy" because the implication it draws is _very_ strong relative to what can probably be evidenced.
In other words, it _is_ the case that Renaissance works were financed with harder money than works today. That's a historical matter of fact. It _is_ the case that families are breaking down or that nutrient levels in produce (per unit size) have decreased. It's also the case that those events were coincident with a change of greater adoption of fiat currency vs hard currency (and I'd put it on a spectrum because of fractional reserve banking and other items which made the Gold standard dollars not _really_ redeemable in Gold and etc).
With all that said, the "sounds crazy" comes in because it's totally unsubstantiated in the quote (and probably otherwise) that just because these things occurred together the change in the status of money is the primary driver behind the other changes.
Edit: For example, if the change in money is the primary driver, then it is the case that the massive technology shifts we've seen aren't the primary driver. Nitrogen based fertilizers aren't the primary driver. Various civil rights movements aren't the primary driver. The presence of global travel, the formation of a global village, the new ability to communicate, none of these are the primary drivers.
And the more you lean on fiat money being the explainer, the less you allow all these other things to contribute to the explanation. That case becomes harder and harder to support, I think.