The government prohibits crypto because it is difficult to control and also crypto price instability. State banks feel that crypto is not needed and many of them think it will be detrimental to fiat later.
the most important is probably the connection with the tax that will be received. there are some prohibitions actually, some prohibit ico, some prohibit the use of crypto, and many more prohibitions. but there are no regulations that can strongly tie the circulation of crypto which makes the government strongly prohibit it. maybe if everyone who has crypto has valid data like we have money in the bank, maybe the government will give permission to crypto.