This is quite a slippery slope. If I host a website in one country, I do not necessarily care where people access my website from. It is not like I actively provide a service to them - they just use internet (decentralised network) to access it. What if I publish a newspaper here, someone takes it where the contents are illegal, am I accountable?
The most obvious example of this is websites from the UK or Europe which operate any kind of gambling. [1] This may well be legal (based on licensing) in their jurisdiction, but they still need to restrict access to prevent US people from accessing the service or they will be breaching the US's gambling laws.
Likewise many US firm geofence access for EU residents out of fear of GDPR.
People hosting news sites have often had to geofence to prevent UK residents from accessing their site if they are hosting any kind of reporting of UK court cases that are under embargo or matters that are subject to one of the UK's famous "Super injunctions" [2]
[1] eg this guy was on the board of a listed UK company operating as far as they were concerned entirely legally who was arrested in NYC https://www.theguardian.com/business/2006/sep/14/gambling.mo...
[2] eg In the "Ryan Giggs" super injunction case https://en.wikipedia.org/wiki/2011_British_privacy_injunctio...
Why not just avoid travel to the US?
And it also extends to countries with extradition treaties to the US; holiday in the the Dominican Republic? You can be arrested and extradited to the US (Gary Kaplan). And of course if you change planes in the US (David Carruthers)? Arrested. Only broke the laws of one US state, and you change planes in another? Arrested (Peter Dicks).
Although perhaps the real lesson there is to be better at avoiding the US.