I didn't invent this interpretation. It's how the word was originally defined, and used for many, many decades, by the founders of the field. See for example:
https://www-formal.stanford.edu/jmc/generality.pdf
Or look at the old / early AGI conference series:
Or read any old, pre-2009 (ImageNet) AI textbook. It will talk about "narrow intelligence" vs "general intelligence," a dichotomy that exists more in GOFAI than the deep learning approaches.
Maybe I'm a curmudgeon and this is entering get-off-my-lawn territory, but I find it immensely annoying when existing clear terminology (AGI vs ASI, strong vs weak, narrow vs. general) is superseded by a confused mix of popular meanings that lack any clear definition.
The McCarthy paper doesn't use the term "artificial general intelligence" anywhere. It does use the word "general" a lot in relation to artificial intelligence.
I looked at the AGI conference page for 2009: https://agi-conference.org/2009/
When it uses the term "artificial general intelligence", it hyperlinks to this page: http://www.agiri.org/wiki/index.php?title=Artificial_General...
Which seems unavailable, so here is an archive from 2007: https://web.archive.org/web/20070106033535/http://www.agiri....
And that page says "In Nov. 1997, the term Artificial General Intelligence was first coined by Mark Avrum Gubrud in the abstract for his paper Nanotechnology and International Security". And here is that paper: https://web.archive.org/web/20070205153112/http://www.foresi...
That paper says: "By advanced artificial general intelligence, I mean AI systems that rival or surpass the human brain in complexity and speed, that can acquire, manipulate and reason with general knowledge, and that are usable in essentially any phase of industrial or military operations where a human intelligence would otherwise be needed."
I think that your insisting that AGI means something different than what everyone else means when they say it is not useful, and will only lead to people getting confused and disagreeing with you. I agree that it's not a great term.