Retail sales? Well, perhaps it's hurting retailers who would have sold a few more low priced physical copies of older games. As for Sony and the publishers/developers themselves, they're probably getting more or equal money this way. More importantly for publishers, more copies of games are getting into the hands of more players, which is excellent for when a sequel is being released.
I know people on gaming forums like to compare copies sold at retail as the only meaningful number but it's not really and is becoming less important of a number every day. Both digital distribution and gaming services like PS+ are going to make retail copies sold a decreasingly less valuable metric.
PS+ appears to be profitable for Sony, and from the games it ends up with every month, I'm guessing publishers and developers are happy with it.
