Probably for collecting donations and moving them through the SWIFT banking system.
I mean imagine if you took donations for some mundane fan art patreon website that ends up violating US copyright laws and you used the proceeds to buy yourself Subway sandwich and a new laptop to create copyrighted art, you are labelled a money launderer.
doesn't such draconian ruling end up driving these type of services deeper underground and closer to actual money laundering which only leads to more proliferation and opacity?