The reason that youths are not played back in following up with the blockchain technology is because of the access to internet. The youths are more enlighten to understand that the world is becoming a global village and they are tapping into whatever is happening in the world, including news and whatelse...
South Africa in comparison could be ahead to other African countries because they are also more technically advanced because of the nature of there acculturation and adaptation
However, don't make your post look like there is already an issue of implementation on cryptocurrency in Africa as you asked because there is barely a country yet to displace there fiat legal tender for bitcoin nor altcoin. They are all trying to work up something and I don't think there is a ban in the use of cryptocurrency in Africa, I have not read that.
There are problems with implementation of Cryptocurrencies in Africa! I understand and you agree Internet connections is one of the challenges we are facing as Africans, The second challenge is Development of cryptocurrencies and blockchain, based on the demand of Developers worldwide, Africa will not be of interest to them that's why there are so many projects but a few targeting Africa.
When it comes to Governement regulations, Few projects operating in Africa are relectant to invest time and resources because they feel regulators might retroactively punish them, For example one of the fastest growing cryptocurrency exchange in Africa was shutdown
https://www.techzim.co.zw/2018/05/golix-ordered-to-shut-down-by-rbz/ Operating in a regulatory Grey Zone is very risky and holding implementation back,
https://qz.com/africa/1278272/bitcoin-in-zimbabwe-has-been-banned-by-reserve-bank/