While the Petro was backed by oil, and no one has said what Irans crypto will be backed by, the question is what is anything backed by.
Fiat money used to be backed by gold.
So what is BTC worth? What is it backed by?
In reality 'money' is not really backed by anything other than trust. "We promise to pay" sort of concepts.
So how does ETH or any other coin gain 'value' or trust?
The most trusted/known coin is BTC, so digitally that probably is the basis of the crypto world.
A gold backed crypto / BTC would be a good thing, and maybe one day it will happen.
In the mean time ETH has a new coin, backed 1:1 by BTC.
This leveraging of the 'value' concept that BTC has will go a long way towards bringing together the crypto world.
If ETH has BTC connections, then XRP could perhaps do the same, along with TTX, EOS and many others.
By doing this ETH which is designed for 'contracts' and works well as a 'process manager' / database type of system will now have 'value' and perhaps stability provided by it's connections to BTC.
An interesting idea. Time will tell if it works out.
https://www.coindesk.com/a-bitcoin-backed-stablecoin-has-launched-on-the-ethereum-blockchain