Also being overlooked is that the nuances in what we accept is in large part how we define group culture.

If you want to use the word 'irregardless' unironically there are people who will accept that. Then there are the rest of us.

Just as an added data point, some languages (e.g. Hungarian) do use double negative “natively”, and I have definitely caught myself having to fight some native expression seeping into my English, including ‘irregardless’. For example a Hungarian would say “I have never done nothing bad” over “anything bad”, but it is used not in a logical sense, but more as an emphasis, perhaps?

(!)Regardless, what I’m trying to say is that due to the unique position of English as the de facto world language, it has to “suffer” some non-idiomatic uses seeping in from non-natives. Actually, I would go even further and say that most smaller languages will slowly stop evolving and only English will have that property going forward (most new inventions no longer gets a native name in most languages, the English one is used).