It has been commonly used and accepted in the case of unknown or unspecified gender, though it is rapidly falling out of favour for that case. In part because I

It has been commonly used and accepted in the case of unknown or unspecified gender, though it is rapidly falling out of favour for that case. In part because I think it's quite hard to say that it's truly 'genderless', it's embedding a 'default' into the language which perhaps is undesirable.