They left the choice for the adfly user that post the link. Enabling the push notifications will make the earnings of the adfly user to increase. But because the notification is annoying to visitors, I do disable it and earn lesser.well, i was talking from a visitor's prespective not an owner, i also don't know why they are doing that, they are disappointing publishers to be honest..
I like the pop ads shown on my website, so I don't use url shortner. I am OK with the pop ads.