You are fighting a losing battle. Think of they/them/their/theirs as being indefinitely gendered third person singular pronouns, as well as being third person plural pronouns. Yes it's a relatively new usage, but I don't think its at all unreasonable (speaking as someone who has been known to dislike some new usages and neologisms). It's not at all sloppy. On the contrary, it's quite deliberate. It's just not quite traditional.
It _is_ sloppy. It says "I can't be bothered to write a sentence that's grammatically correct".
You need to get over that.
I don't need to get over anything. If someone sends me a document that uses "their" in a singular usage, I will think that person is lazy. That will continue to be the case, whether people tell me that it's accepted usage or not.
In much the same way, I know that I can safely discount the opinion of anyone who uses "literally" to mean anything other than "literally"
(
similarly anyone who uses
"like" as a quotative)
, even though both of those things are now in fairly common usage.
Your proposed style would make writing docs a lot harder,
I don't buy that at all. It takes a couple of seconds, if that, to come up with something.
forcing us to avoid use of the singular in cases where it is quite natural.
Better than using the plural in the singular case.
I'm strongly opposed to such a style rule.
Meh. I don't really care how it's written, certainly not enough to make a stand about it. I'd rather you guys concentrate on writing the brilliant software than wasting time on stuff like this. I only replied because the conversation popped up in my inbox and it seemed to be something on which opinions were requested.