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I'm sorry if being gender-specific offends some whiny little SJWs but accuracy is more important.
Singular they has been in use since the 16th century, its not an invention of these past decades, id consider it a part of English
https://www.oed.com/view/Entry/200700According to the source you cited (OED) it has only been used for specific individuals more recently.
In the 21st century, other th pronouns (and the possessive adjective their) are sometimes used to refer to a named individual, so as to avoid revealing or making an assumption about that person's gender; cf. sense A. 2c, and quots. 2008 at their adj. 2b, 2009 at them pron. 4b, 2009 at themself pron. 2b.
Language is ever-changing, not always for the better. This is a case of obscuring gender, of replacing clarity with vagueness.