"preferred (but not required)" is what wikipedia actually says, along with generic-he being the current usage (not rule).

Interestingly wikipedia also states "In the 19th century, grammarians in England petitioned the British Parliament to declare gender-indeterminate pronouns as 'he' rather than 'they', which was common usage at the time. "

The english language is far from a codified, logically consistent system.

It's not really any less correct than a genderless pronoun, even if one particular panel disagreed. I see no reason to use a masculine pronoun when a generic one will do, and could only call it "political correct nonsense" if an author insisted on either alternating between he and she, or used "he/she".

I find things written with lots of genderless pronouns can make the writing unclear. Lots of "They" , "Their" feels unnatural and clumsy when talking about people and it can become difficult to decipher which parts of the text are referring to a person and which to some inanimate thing.

Just as frustrating is writing that switches pronoun gender when referring to ostensibly the same person. However describing some operation between two people "Alice and Bob" it can improve clarity to make both people belong to different genders.

Every modern dictionary disagree. English usage of singular they dates back to 15th century still you assert it here without any argument. Nothing wrong with asserting things if you do that with stuff disprovable by one dictionary/wikipedia search though you make not too bright impression to put it mildly.

As to using she it's very common convention these days in some domains. Many books on games use that for example (chess, bridge, go, poker - you need to a pronoun for black/white/last to act player there ). I also saw some computer science books using it. At this point I would say it's so common that it becomes part of the language. I personally like it although I can see how it raises eyebrows when encountered for the first time :)