But what do you mean by "targets based on a specific identity?" Clearly the intent is to target the same person who went to a site but did not convert. That sounds like targeting based on a specific identity to me.
Also, I can name at least two companies that target people (OK, cookie stores) based on specific interests or traits they (OK, their users) are surmised to have: Google and Facebook. These two are very high-profile about it, so I would be surprised if others did not do the same.