As you are acknowledging, that "choice finalization" was made on 2018. 3 years after you backed the game and payed the money. I guess you would, at most, be entitled to change your choice of the "Steam" version (now non-existent) for the PS4 one, or even insist on getting a Steam version. But not to a refund. The lie is repeating that backers were promised a Steam version. Because when they actually and freely became backers, there was no Steam promise.