The answer is very simple - in the presence of technological advantages, decentralization and uncontrollability by the state or specialized structures does not allow this solution to be used at the level of the state financial system! Never (in today's world), no state will allow its financial system not to depend on it!
this is still propaganda. people think that because it can't be controlled, the government doesn't accept it as a legal transaction tool (although some countries have started to legalize and start making regulations about it). however, the reason is still the same, it's because of the rampant fraud that mentions the name of cryptocurrencies, and there are still many unfulfilled regulations of cryptocurrencies for some countries. however, for now it is good enough that cryptocurrencies are still allowed as an investment tool by many countries. it can be a trigger little by little crypto is accepted among the public before it grows even bigger.
Although it should be added - I am sure that some of the blockchain technology solutions will be integrated into today's banking and financial solutions! And the technology itself is already used in the non-financial sector quite often.
Right. I've read some information about banks trying to develop a blockchain system for themselves. In fact, China is also developing their own cryptocurrency but still rejects other crypto. well, I still pay attention to such information.
I agree that I also forgot to indicate the high probability of fraud and the irreversibility of transactions. But this problem is a derivative of the advantages of technology, as it happens in our life, and there are many more examples ...
And the fact that technologies will be adopted in real sectors of the economy - you can not even doubt. For example, an interbank blockchain can be built, with its own security implementation (for example, as in YUSDT where you can block tokens), exclusively for interbank interaction. I know that some information registries are already using blockchain technology. The same work of notaries - this is the purest blockchain, where technology guarantees the immutability of notary records, which will make it impossible for many fraudulent schemes!