Cryptocurrency exchanges representatives announced record new users registration rates last year in autumn. Binance said that they had 250000 new accounts per day, while Coinbase had 100000.
Such high demand causes problems for cryptocurrency exchanges. As a result these services operated badly. Then Binance, Bitfinex and Bittrex temporarily stopped registration of new users.
Bitfinex explains their unwillingness to register new users:
Recently Binance also had to stop accepting registrations after the system update. However, the other day the announcement appeared informing that the exchange opened a limited registration of new accounts:
Bitfinex announced that it would start accepting registrations from January 15th, 2018, however, Bittrex and Binance did not mention the date when they accept registrations of new users again.