Why do you think a bitcoin core developer wrote the FAQ? In a large project like this it is not at all unusual to have documentation written by people outside the core development team. In fact you can go look at the history of this page, David Harding wrote most of it and I do not see any commits from him in core.
Part of having effective communication is having people on your wider team that are experts in that area, even if they aren't one of the people writing all the software.
