Based on the examples on the page it doesn't look like they are doing that. They are talking about the "user" which depending on context might be the programmer using the API or the end user using the application.
But I think this gets to the root of the problem. Text with generic pronouns can get clumsy , especially so if the grammar is less than perfect.
"He" or "She" removes any ambiguity that you are referring to a singular person. Whereas "they" could mean a single person, a group of people or some inanimate object. So a gendered pronoun can make your writing clearer but of course forces you into a specific gender.
Historically "He" was often used as a pronoun which could be considered either gendered or gender neutral dependent upon context.
But I think this gets to the root of the problem. Text with generic pronouns can get clumsy , especially so if the grammar is less than perfect.
"He" or "She" removes any ambiguity that you are referring to a singular person. Whereas "they" could mean a single person, a group of people or some inanimate object. So a gendered pronoun can make your writing clearer but of course forces you into a specific gender.
Historically "He" was often used as a pronoun which could be considered either gendered or gender neutral dependent upon context.