It would actually be pretty sweet if something like PiHole bundled and incorporated something like this as a configuration option, to deal with sites where DNS-only blocking didn't work.
As Privaxy includes blocklists, I'd argue that it is a superset of PiHole functionality. DNS blocklisting is actually pretty straightforward, and there are many tools which do it. PiHole is only one.
That said, which would be better suited to incorporate the other is an interesting question.