How does the policy HELP sales?
I never said it would help sales. I don't think it's any different than loaning a disc out.
Loaning a disc out doesn't hurt sales nor does it necessarily help sales. If the person who got to play the game liked it, they'll buy it, but if they can't be bothered buying it then they won't.
Same will hold true with lending a digital copy. Someone may like the game a lot and want to buy it after playing it. If they do, there is a sale, but if they don't, there isn't.
It's a 1:1.
DRM may be a giant dildo up the anus, but with a good amount of lube and a little patience, it actually feels quite good. Or to put it less poetically, DRM doesn't have to be painful. It can give you as good of an experience as having a physical disc can.