As a former senior civil servant in Hong Kong for decades, I believe stakeholders in the relevant sector know me. There has been quite a lot of information about me over the web and there is not much I can hide. Further, I publish a lot of copyright works on-line and want to give notice of my copyright ownership in my name.
I understand the risk my relative on-line transparency might bring. While there is no way of knowing a friend's subjective intention, one way to detect scams is to discern inconsistency between what a friend claims and the external circumstances. Eg if a friend claims s/he does not use FB that much, but in fact s/he is active all the time.
As a thin safeguard, I might add a friend if s/he is already a friend of a friend. However, a friend's friend might only actualize as a scammer when the emotional or "trust" relationship is established. Only then would a scammer ask for personal identity particulars for theft, or money to help out in "emergency" situations etc.
When a "friend" asks you to leave the social media platform to engage in private chats, be alert, as this is the first signal of scamming. Early scam detection helps us not wasting our time, spoiling our feelings and losing our money. In on-line relationships, I believe playing safe rather than taking risk should be the best policy!