It's no longer common (hence my surprise when someone does it) but it's not an utterly unfamiliar usage, either.
"No one" doesn't literally mean "a number of people which is equal to zero".
I reflected on that before I posted my comment. Here are my thoughts.
Even if I read "no one" as "a nonzero but negligible number of people", Azathoth123 is probably still wrong. I can name only one person who's said "black" to me with the meaning "South Asian" in mind, but then I've only met a tiny fraction of all Brits; chances are there are thousands of other people out there using the term in a similar way whom I just haven't met. That this was a relatively frequent usage before 1990 or so makes it all the more likely. (See also "Moslem", which has been almost wholly displaced by "Muslim" in everyday speech here, but which I hear (albeit not that often) from middle-aged and old people, quite often see in old books, and occasionally encounter in more recent texts by non-native writers of English, like this book.)
Moreover, it's a bit of a bad habit to write claims which are false when read straightforwardly & literally. It's better to avoid writing things which are only true if read generously, to minimize the risk of planting falsities in people's heads. Qualifiers are not expensive. (If you've ever wondered why I lean on adverbs like "relatively", "occasionally", "rarely", "mostly", "likely", "probably", "almost", "nearly", "hardly", and "presumably" as much as I do, you now know why.)
Moreover moreover, asserting not-quite-true things makes room for mischief. If you're arguing for some conclusion C which gets more convincing if your premise P is less qualified, there's a temptation to grab illicit rhetorical power by asserting P too strongly in a plausibly deniable way, gambling on no one noticing; and if someone does flag it, you can just say you weren't really asserting P in its bluntest form, even if that's literally what you did. (I am not saying Azathoth123 consciously did that here, not least because their conclusion — the social meaning of "race" isn't just about appearance — still mostly goes through if you appropriately weaken their premise. I just think this general phenomenon's another reason to take notice of false-as-literally-stated assertions.)
It's better to avoid writing things which are only true if read generously, to minimize the risk of planting falsities in people's heads.
But this amounts to "it's better to avoid talking the way that pretty much every human being not in a minority of literal-minded Internet users talks in most contexts".
there's a temptation to grab illicit rhetorical power by asserting P too strongly in a plausibly deniable way, gambling on no one noticing
This is of course correct, yet it still doesn't change that.
And the correct way to respond to someone...
It's that time of year again.
If you are reading this post and self-identify as a LWer, then you are the target population for the Less Wrong Census/Survey. Please take it. Doesn't matter if you don't post much. Doesn't matter if you're a lurker. Take the survey.
This year's census contains a "main survey" that should take about ten or fifteen minutes, as well as a bunch of "extra credit questions". You may do the extra credit questions if you want. You may skip all the extra credit questions if you want. They're pretty long and not all of them are very interesting. But it is very important that you not put off doing the survey or not do the survey at all because you're intimidated by the extra credit questions.
It also contains a chance at winning a MONETARY REWARD at the bottom. You do not need to fill in all the extra credit questions to get the MONETARY REWARD, just make an honest stab at as much of the survey as you can.
Please make things easier for my computer and by extension me by reading all the instructions and by answering any text questions in the simplest and most obvious possible way. For example, if it asks you "What language do you speak?" please answer "English" instead of "I speak English" or "It's English" or "English since I live in Canada" or "English (US)" or anything else. This will help me sort responses quickly and easily. Likewise, if a question asks for a number, please answer with a number such as "4", rather than "four".
The planned closing date for the survey is Friday, November 14. Instead of putting the survey off and then forgetting to do it, why not fill it out right now?
Okay! Enough preliminaries! Time to take the...
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[EDIT: SURVEY CLOSED, DO NOT TAKE!]
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Thanks to everyone who suggested questions and ideas for the 2014 Less Wrong Census/Survey. I regret I was unable to take all of your suggestions into account, because of some limitations in Google Docs, concern about survey length, and contradictions/duplications among suggestions. The current survey is a mess and requires serious shortening and possibly a hard and fast rule that it will never get longer than it is right now.
By ancient tradition, if you take the survey you may comment saying you have done so here, and people will upvote you and you will get karma.