No, that is simply not true.  All forms of money are a recursive belief system.  They are the belief that a certain asset will be accepted by others against something valuable, because they believe the same thing.  That's all there is to a monetary asset.  There is no "backing" of it by anything, it is just pure belief.  I am willing to provide value in return for the monetary asset X, because I believe that I will OBTAIN value again when spending it,  simply because the next guy will hold the same belief as I do.

However, in order for that belief to be sustainable, the belief must be held too that one cannot create AT WILL the monetary asset out of thin air.  I'm not going to deliver value for X, if you can make X out of thin air AT WILL.  

On the other hand, X has to come from somewhere.  So it has/had to be created, found, dug up, .... whatever.  In a monetary system, one ACCEPTS a way of creation of "legit" currency.  Because it is the state, because it can be dug up from the ground, because one has to spend effort on it, because there's a fair competition in doing so.... WHATEVER reason that is considered fair/legit/acceptable, and this must be the ONLY way of making X.  We can accept that the state prints it (because we believe that the state is there for the common good) ; we can accept it that the king prints it (because we are humble servants of his Majesty) ; we can accept that one digs it up (because we could also dig it up) ; we can accept that it is mined (because we can also mine it) ...

But there must be a LEGIT way to CREATE the currency X, and no other means.  One way to create it, but surely not the only one, would be the John Law kind of issuing of currency, namely creation of certificates, the way you illustrate it.  But as I said, that's just ONE way of creating a currency: as "certificates of ownership of something valuable".  It doesn't have to be that way, and in fact, most of the time, it isn't.

The only other thing we must be sure of, is that transactions conserve the total amount of currency ; or, stated differently, that there is no double spending.

Once that's in place, the belief system is potentially sustainable, and that's all there is to it.    We then know that the only currency we can receive is from a legit origin, transmitted through transactions that conserved the total quantity of currency, and that we will be able to spend exactly that amount, once.

The idea that currency has to be "backed" by something of value is erroneous.  It is just a recursive belief system, nothing more.  A belief system that there is legit creation of tokens and that these tokens are transmitted in conservative transactions.

Gold is also a belief system. Gold has some intrinsic usage value, but that is only a tiny fraction of its market price.  It has some usage in jewels and technology, but that's peanuts.  Gold has value, because people think that other people value it.  That's not "backed" by anything either.  The day that people decide that gold has only technological value, its price will plummet to the price of, say, lithium or cobalt.

That said, the "backing" of a currency can be part of the belief system: if you BELIEVE that you are entitled to something of actual value against the currency no matter what, this is a way to give value to a currency through the value of what backs it.  But it is not a necessity.  As I pointed out, gold is not backed by anything and has monetary value too.

The idea that the modern fiat system is backed by anything is also ridiculous.  It isn't.  It used to be backed by a lie, namely "gold" or "silver", but when it became too obvious that that wasn't the case, people gave up, and now, central bank money is simply not backed by ANYTHING.  "future economy" or whatever is a joke invented to instil confidence and to sustain the belief system.  If there's hyperinflation, you SEE that it wasn't backed by anything.

Money is just belief.  The belief that someone else also believes that it has value.  And it works.