It seems to be a real anthropology concept, and it kinda makes sense for my experience as french, i guess you could be in a relationship without saying “we are bf/gf”, though it seems odd to not talk about your feelings if the relationship goes on for multiple dates.
I don’t know what i think about this concept, partly because one justification is “countries with a very diverse population are more low context” and france is a mix of a lot of cultures, but i guess it’s true in some ways.