PDF won't help her, because sophie is speaking about a client that probably wants to edit the files, and InDesign doesn't do that with pdf.
It's a big problem for us designers not to be possible to export idml files. When we work with a team/client that uses InDesign, we need to send them the files in idml, thus everyone would be happy editing the same files. It would be a great thing if Affinity could improve that in Publisher, at least (to be able to export idml). I think Affinity would have a lot of new users because of that.
When I received the e-mail about Affinity 2, I thought "omg, something big is coming? Maybe finally they made that!", but no...