The actual reason you can't trade on many offshore brokerages crypto or not, is because of the CFTC regulations regarding trading. the CFTC requires any brokerage that accepts US clients to register with the CFTC and then hold US clients to CFTC standards. Most brokerages just decline US clients. Go to any respectable Forex broker online. pepperstone, icmarkets, etc. and you will also see they do not accept US clients. it isn't because they are scams, it's because they can have lawsuits filed against them in their operating country by the US government.
RE: WTF! Due to local laws, Bitmex is unable to service your country(US)!