As a living language, English has no shortage of quirks and ambiguities but tends to adapt over time to fill the semantic gaps. However, there is a big difference between the natural evolution of language and compelled speech.
Unlike some other European languages, English lacks a generic gender-neutral pronoun such as the German “man” or French “on” for the third person singular, although the formal impersonal pronoun “one” may sometimes meet these needs. By and large, we find ourselves having to choose between he/him/his and she/her/hers when referring to an abstract third person.
Someone, anyone and everyone may take the third person singular verb, but have long, especially in everyday speech, been combined with they, theirs and them, e.g. “Someone has left their keys on the table” or “Everyone should take their belongings with them”. Older style guides recommended third person singular pronouns with “someone” or ”anyone” when they refer to one person only and until recently he/him/his was the default even if it could involve a woman. By contrast, "everyone" always refers to more than one person. Besides, the inclusion of “someone” or “anyone” in a sentence removes any potential ambiguity when combined with “they/them/their”, but this is not the case when a pronoun acts as a placeholder for a singular gendered woman or man.
Yet on the back of the gender-bending craze, third person plural pronouns are creeping into contexts where we’d expect singular forms unless many people are involved. I now get emails from LinkedIn with phraseology like “Angela Green has accepted your invitation. Message them now!”. As Angela is clearly a singular woman, will my private messages to her be sent to more than one person?
I’ve long observed that modern English has a stronger tendency to use people’s names in sentences where other languages would omit them, partly to avoid ambiguity in sentences like “Michael drove Bill to York in his car” where “his car” may be Michael’s or Bill’s. What happens if misplaced political correctness leads us not to assume Michael or Bill’s gender identities and instead opt for phraseology like “Michael drove Bill to York in their car”. Does this mean Bill and Michael share a car, but Michael drove on that occasion?
How could a language evolve without a means to identify a gendered person in a respectfully neutral way? The answer is simple. Human sexual dimorphism plays a central role in all traditional societies. Besides, gendered singular pronouns are deeply ingrained in everyday speech. Most suggested alternative gender-neutral pronouns either clash with common names or just sound hackneyed, especially as most people still like their natural gender identity.
The growing use of they/them/theirs for singular males or females dehumanises people. It promotes a rejection of our natural heritage as the offspring of a long line of women and men and blurs key distinctions between a group of people and a free-thinking autonomous individual rather than a mere subject of a genetic experiment.