Whats the deal with Skype?

I see it referenced in a lot of these trade threads yet from what I have seen, no one actually uses the voice/video chat features. It seems to be used just for text communication, no actual security features or at least seeing the face of the person who is about to scame you.

Why not just add on facebook instead so you at least have a face to add to the indentity.

...or am I misunderstanding the purpose of Skype entirely.

 

If you video or voice chat you have no history of the chat/trade ever occurring for proof.