Earlier quoted context omitted.
Funny how everyone talks about the Chinese "great firewall" that blocks access towards some western platforms from China, and no one talks about "USA great firewall" that blocks Cuban citizen from acceding to a lot of services
Because the latter is not a thing. The United States does not implement any border firewalls on traffic entering the country. No law compels blocking Cuban citizens from accessing US hosted content, just preventing them from entering into financial transactions.
Let me give you an example: I can't open dell.com, at all. What I want to believe is that they blocked all access because it was easy, just a geo thingy flipped on. It is their decision though, but it is supported on existing sanctions. So... yes, the law compels them to do it, indirectly or not. And there are hundreds, thousands of other examples that I can provide, if you're interested.