@DeaTh-ShiNoBi I can speak with a little confidence as to why it's in the deck, and the desire to metagame against combo decks was definitely one of the factors in its inclusion. Pitch Dredge (specifically the Mindbreak Trap / Chancellor of the Annex variant) was developed in response to the MTGO Classic (Vintage minus key power cards) environment immediately before the release of Vintage Masters. In that environment, Belcher and other combo decks had an outsized presence and I simply kept Mindbreak Trap in the deck as long as it was performing well and there was no better replacement.
I do think there is merit to the concept of replacing Mindbreak with Prized Amalgam in "pure" Pitch Dredge, but a big part of the appeal of Mindbreak is the value of the card post-board and in the relevant matchups. I think only time and testing will distinguish which is more important. My intention at the moment is to sit on the sidelines for a bit and watch the metagame develop, and either to run with the ideas that others develop around Pitch Dredge (Glackin's list is exciting) or to eventually form a new list for myself.