This is the case, and has always been the case.

It is pretty common for people to sue international publications for libel in the UK under UK libel laws on the basis that the site has British readers.

The US decided to unilaterally breach it's treaty provisions on that front and doesn't enforce British libel judgements (you may think this is a good thing, but that is what actually happened), but notably if you ever visit the UK as an American publisher you're still liable...