The total economical power of these contries are very small, so overall cryptos are allowed as a payment method.
ICO´s have different rules but that is not to interesting, since you can just launch the ICO from which ever country you like and it wont affect adaption as much as prohibiting use of crypto for payments..
https://en.wikipedia.org/wiki/Legality_of_bitcoin_by_country_or_territory
There is also many contries that is black listed from big exchanges. Bithumb for example recently banned the following countries for complying with new anti money laundering and terror FUD!
Bosnia and Herzegovina, Ethiopia, Iran ,Iraq, North Korea, Sri Lanka, Syria, Trinidad and Tobago, Tunisia, Vanuatu, Yemen
Not the biggest contributors to the world economy either
But why these countries banned? Do you know it?