The same reason was stated by the central bank in my country but they only warned people on how risky in using cryptocurrencies in their transactions. Cryptocurrencies like bitcoin are not legal nor illegal in my country and the usage of the virtual coins keep growing daily. I think it is better if government start an information campaign on how to properly use cryptocurrencies instead of giving only warnings to those who use it.
If the government care that much they can do some informational campaigns regarding to this currency, there's some info drive to make people around the country to be aware and not to fall to any attempt of scammers and to avoid losing money.