You should have a view of the Localbitcoin.I had experience from long and you should check that.Because it had low incoming transaction fee and sending transaction fee.
You have no idea what margin trading is, do you?
So, people could move their money towards margin trading websites that are not based in USA and they can do their margin trading there, it would be simpler for many.
Bitmex was not based in the US, there is no place on this earth that will keep you safe if they want to come after you. Even the whole based in Russia and be safe from the US myth was shattered in a billion pieces with BTC-e.
Coinbase seems to strive to be as government-friendly as possible, in contrast to exchanges like BitMEX whereas they're pretty much always at the center border of being legal and illegal.
Yeah, that's the main thing, they have offered margin trading for a long time then decided to restrict it since by the time of the GDAX scandal and started on different terms with Pro, but probably it's begging to be too much of a hassle and bring in way too little money to live with a dangling ax over your head all time time. They are trying to do everything they can to be on the best terms with every authority, certainly, they are having tons of bitcoins in their pockets and made a lot of money already so they prefer to enjoy those from the outside.