> The line has to be drawn somewhere to prevent garbage from making its way into open standards.

Given that the term is explicitly mentioned in the Chicago Manual of Style, I suspect that this is much more of unicode trying to capture existing behavior, even if rare. And I think it's important to err on the side of capturing what people did, even if it's from an bygone era.

> How many people actually use this thing? 10 loud people with power using it does not justify putting it into the open standard.

It's definitely more than 10. But even if it's 10, I disagree with your assessment. People used this; it's worth a codepoint. There are far stranger code points out there.

And I've seen far weirder things in open standards. Have you read the C99 standard? Are you aware of the three allowed integer representations? Of which maybe two were in use in 1999, and one only in use in relic hardware that might exist in maybe tens of sites.