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?
> We have been clear that exiting the UK does not allow an organisation to avoid responsibility for any prior infringement of data protection law
In that context it's completely fair to say "leaving doesn't absolve you of past transgressions".
Edit. If Imgur made any revenue from UK users then it becomes impossible to claim plausible deniability on any definition of "providing a service". If the UK can do something about this is a different matter. They could make CEOs/board personally or even criminally liable for the company's failure to pay a fine but probably won't.
I sell a advertising package from my US HQ based self serve advertising portal to a British company who use the service to advertise to customers in the UK. Ok - kinda UK revenue. How about 'To advertise to customers in the US' well it's getting highly debatable.
What about I sell advertising packages to a US company from my US HQ but someone in the UK views and advert on my site and therefore generates me 0.001¢ - debatable.
But I didn't say "in the UK", I said "from UK users". If Imgur monetized anything coming from a user in the UK then they can no longer pretend they weren't offering a service. They knowingly used that data to make money, it wasn't that someone accessed the site and that was the end of it.
It's the difference between going in and out of a restaurant, compared to sitting down, checking out the menu, and eating then refusing to pay because the prices are ridiculous. The latter removes any pretense of deniability. If they disagreed with a ridiculous law they should have put in a modicum of effort to block the service in the UK from the start. Instead they made money for as long as they could and now pretend to stand up for the little guy and fight abuse.