Sometimes I find it useful to fall back to basics.
Powerful economy doesn't mean that you have less fiat tokens to represent the same amount valuable assets. It means that there is more real valuable resources being traded around.
If each paper bill represents an amount of something owed to someone by someone else, then it is logically attributed some value.
It is also logical that the economy doesn't need to become weak because the amount of such tokens circulating increases as the amount of goods and services available for trade increases.
There are a few things in the interveiw about how money initially came to be that are too simplistic. She says that the reason people were said to agree on gold was only due to intrinsic properties with no mention of scarcity which is perhaps the most important factor to consider when discussing inflation of all things.

Just my opinion of course. Not a scholar.