@glitzersachen Even the most fastidious inclusive language users in my hometown use the word "guy" to refer to a girl for exactly the same reason most English speakers use "goose" to refer to a large waterfowl even if it they know it's a gander.
I've lived in a different place where using "guy" to refer to a girl will get you looked at like you have three heads and the plural usually is only used for groups of boys.
@glitzersachen The US altolect is somewhere in the middle, disallowing "guy" to refer to a girl and being a bit squeamish about using "guys" to refer to a group of girls.
If the dialect I grew up with was the altolect, would we be having this conversation? Maybe, but I doubt it. English has a lot of words that are marked for gender only when used contrastively, and no one really complains about any of the other ones.
@glitzersachen The only reason this is an issue is because the altolect is kind of wishy-washy, and the altolect is the altolect because the most privileged people tend to speak it. That means the discussion has classist and regionalist underpinnings even if people don't realize or want to acknowledge it.
None of this is an endorsement of calling anyone anything they don't want to be called, of course.