I honestly don't know where people trade at anymore, or how a us citizen even could effectively trade in this market with all the options we've had taken from us.
US is the is ranked 1 as the biggest cryptocurrency possesions before china, so i think making the exchanges that only for US users is good decission since the volume of their daily trades will be already so high. Just like binance for creating binance US and other exchanges that make US exclusives exchange.
Creating separate exchange for US customers doesn't give any assurance of people will use your exchange when more exchanges with a good reputation are already existing but you will face the regulatory issues just like any other exchange.