I mean, I get what you're saying, from a consumer standpoint especially. All I'm saying is that I also get where publishers are coming from when pricing a game like that in this way (full price), as its existence on another platform, which you, as a paying consumer, are seemingly not interested in anyways, doesn't really have a huge impact on the current pricing decision, especially if it's been only one year (and not, like, three or more with stuff like Horizon Zero Dawn e.g., which still was only 10€ less on Steam than originally on PS4 at release in 2017).
Long story short: maybe it's just me, but OT being full price on Steam in 2019 doesn't seem too surprising to me, even with it being a late port of a timed exclusive.