Either that or tadpoles are Hell's bitcoins. I mean, let's look at the mechanics of these tadpoles: they are able to connect between them, the actions and thoughts of the infected PC can manipulate other tadpoled creatures (suggesting that they have the potential to become an elder brain) and they are incredibly resistant / protected by Netherese magic. If I was a soul-hoarding devil I would do anything to get my hands on an infected host, as with "the proper guidance" any one of them could mind-control a lot of other people into selling their souls to me. It's a get rich quick scheme.
