Why do scammers use victims' computers to remote-control their own computers?

TeamViewer has noticed that scammers often come from India (or other places where scams often originate), and so when you get an incoming connection from India TeamViewer will give you a warning saying that this could be a scam. If the scammer can get the victim to connect to the scammer's computer first and then reverse the connection (by clicking a button that says "switch sides with partner"), TeamViewer's warning is skipped and the victim still doesn't know it's a scammer. The scammers want to use TeamViewer because it has the ability to blacken the victims screen so the victim cannot see what the scammer is doing.

A Youtube reference