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?
It's not about "hosting a website", it's about providing services.
If you provide services, like selling a newspaper, in the UK, you need to respect their laws, or you will suffer the legal implications of not doing so.
And regarding the accountability, it refers to the fact that imgur USED TO provide services in the UK:
> We have been clear that exiting the UK does not allow an organisation to avoid responsibility for any prior infringement of data protection law, and our investigation remains ongoing.
Companies providing services outside the UK can infringe all the UK laws they want, the UK doesn't care.
But as soon as you decide to provide services in the UK, you have to follow the law. And, as they explain in the article, if you break the law, stopping to provide services in the UK will not absolve you for your past wrongdoings.
Meaning that the servers were located in the UK, or that the users were, or both?
Whose laws need to be followed?
Does it also count for people in the UK using a vpn? What about people in the UK paying using American money? It’s not clear, but it doesn’t really matter. These laws target the service providers, not the customers. If you website says “this product isn’t available to UK residents” and you IP block and don’t take GBP as a payment method, nobody will get too angry if a spattering of tech savvy people get around the block using a VPN.