Cryptocurrencies have reached a new stage of development after blockchain applications have gained traction, says Yale University’s Aleh Tsyvinski. : Cryptocurrencies have reached a new stage of development after blockchain applications have gained traction, says Yale University’s Aleh Tsyvinski. NEW HAVEN, Connecticut: Regulators around the world are cracking down on cryptocurrencies. China has banned them. The United States is considering a range of measures aimed at reining them in. But, far from spelling disaster for the crypto industry, regulation is vital to its long-term prospects.