As I understand it, a primary feature / requirement of cryptocurrency is that it is not controlled by a government actor: it is decentralized. If this is true and the Petro is controlled by a government (i.e. it can 'mint' more coins):
What is the reason to implement cryptocurrency in a manner that allows for greater ease of 'printing money'?
Cryptocurrency is never a good medium of trade exchange compare to printed notes.
Anyone follows the history and trend of cryptocurrency can tell you that, cryptocurrency has become speculative medium than a currency itself. The best scenario to describe the speculation is various Initial coin offering(ICO) that went boom and bust.
A cryptocurrency such as Petro coins does not fair better than others, even Venezuela government say it is "backing" with something like oil. Because the logistics are too complicated and costly. Thus, Petro coin is anything but just yet another ICO to attract speculators to pay it in dollars(or any foreign currency that Venezuela needs).
In short, something like Petro is not going to replace the currency, but as a tool or "virtual commodity honeypot" used by Venezuela to get foreign currency without any sound production.
Its a type of control fraud. Not only is there a lack of decentralization as you have noticed, but the petro cannot be converted directly into deliverable-upon-demand oil contracts. Remember, the petro is supposed to be backed by oil.
It's important to understand that any currency that claims to be "backed" by gold, oil, rice, bat guano, etc. must be convertible to the underlying commodity at a transparent conversion rate.
If a currency can't be converted on demand into the underlying commodity, it's not "backed by oil," it's just another form of control fraud, which I define as those holding power in centralized institutions enrich themselves at the expense of the citizenry by modifying what's legally permissible.
Conventional fraud is against the law; control fraud is legal because it benefits those who make the rules.
Until a foreign financial institution successfully converts its Venezuelan petros into actual barrels of oil, or oil contracts that can be sold immediately on the global market, then the petro isn't backed by anything. Until that conversion process is functioning transparently, the petro is nothing but a giant control fraud perpetrated to benefit the few clinging to power in Venezuela at the expense of the many.
Cryptocurrencies are technology, but their value comes from a "social contract", people agree that the "asset" created by the blockchain is of some worth. You can take the bitcoin code, make a copy, change a few parameters and rename it to "myCoin" and sell those coins to your friends, but there would be no social contract in place to give it value.
Cryptocurrencies dont HAVE to be decentralised, they can and probably will be issued by governments in the future (and I suppose Venezuela has already), bitcoin is what is called a "permissionless" crypto, meaning you don't have a central authority to appeal too if someone steals all your coins, but "permissioned" cryptocurrencies will allow a central authority to have the final say, think about land tokenized onto a blockchain, the local government in charge should be administering it, and your land shouldn't be able to be stolen from out beneath you like bitcoin could ("sorry mom, we have to move, Bob got our private key and stole our house"). Also, bitcoin can't be inherited without making plans to specifically do just that, think about the Canadian crypto-exchange that lost access after the guy in charge died, no one had access to the private keys, so no court could make a ruling to move the money, cause it's not possible without the lost private keys.
Technically, Venezuela issued their own currency, but the trust is not there in the government, so that lack of trust extends to their self-issued cryptocurrency as well.
