Language only evolves, "devolving" isn't a thing. All changes are arbitrary. Language is always messy, fluid and ambigious. You should go with the flow because being a prescriptivist about the way other people speak is obnoxious and pointless.
And "literally" has been used to mean "figuratively" for as long as the word has existed[0].
I'm going to take a rosier view of prescriptivists and say they are a necessary part of the speaking/writing public, doing the valuable work of fighting entropic forces to prevent making our language dumb. They don't always need to win or be right.
That's the first time I've seen literally-as-figuratively defended from a historical perspective. I still think we'd all be better off if people didn't mindlessly use it as a filler word or for emphasis, which is generally what people are doing these days that is the source of controversy, not reviving an archaic usage.
Also, it's kind of ironic you corrected my use of "devolves", where many would accept it. :)
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).
And "literally" has been used to mean "figuratively" for as long as the word has existed[0].
[0]https://blogs.illinois.edu/view/25/96439