(SaltPans - I am not sure if you intended to attribute it to me, but the phrase you quote: the fantastical idea that a phrase arose in the late Middle Ages but no one ever wrote it down in any form of work in England or in Ireland for hundreds of years. That’s so unlikely as to be immediately discountable was originally posted by Ruffina and quoted by me in italics).
I absolutely agree with you that what was committed to paper in the late medieval/early modern period did not necessarily reflect everyday speech, and therefore the 'earliest recorded written example of the phrase' argument (the etymology argument) is irrelevant to the history of the phrase.
However, I disagree with your 'Hi' example. In this case, it's not a different language we are talking about. Of course there are phrases in other languages that have meanings in English that are a far cry from the English meaning. Nobody is contemplating a comprehensive weeding out of every syllable that might mean something different elsewhere.
The meaning of 'beyond the Pale' has never changed. It always meant 'beyond what was acceptable'. What has changed is that many people have forgotten that that which was unacceptable was the Irish, Irish customs, Irish language, Irish (Brehon) law.
we cannot inhibit the evolution of living languages, by insisting on references to historical meanings
We can, and in fact we do it all the time. The pace of weeding out of words and phrases based on historical meanings has accelerated in recent decades.
We no longer use many slurs or metaphors or similes that were once commonplace. In deference to MN's policies on this I will not list them here but the slurs I refer to are against black people, Jews, native Americans, people from Pakistan and India, gays, lesbians, women in general, and the list goes on.
I was born in the 60s and remember a programme called 'The Black and White Minstrel Show' in primetime on BBC. It ran until 1978. Would it run now?
The Prime Minister in her Tory Party conference speech of 2016 referred to 'citizens of nowhere' and was roundly and rightly criticised for that. It was an old reference to Jews (aka 'rootless cosmopolitans') and raised many a hackle. A short memory is no excuse for use of language that is offensive.
What do you think people who whine about 'PC running amok' are complaining about? They are in their own way complaining that language has been stripped of all its joy, vigour, etc. All the joy that was in it for them, that is...
Northern Ireland has its own set of slurs used by both communities, but just because the average English, Welsh or Scottish person might not know what any of them mean doesn't mean you can use those slurs in everyday speech after you have been told they are slurs and that they offend. It doesn't matter that the terms have been used for over 200 years. It doesn't matter if you personally mean no harm or offense if you use them.