it is partly that but also it is about all the illegal activity that took place thanks to altcoins last two years. you see all these ICOs and think they are just scamming a bunch of newbies but many of them were actually laundering money through fake ICO front and cleaned their money by simply running it through that fund raising crap and dumping it on exchanges.

Anti-money laundering rules typically require banks to know the identity and aims of their clients and often be able to trace the source of their customers’ cash. Building a compliance and monitoring system is expensive and some banks conclude the costs just aren’t worth it.