This is not about people who are certain to buy all the DLCs or even regular fans of paradox that follow the news, read the DDs and so on. They will buy DLCs no matter what, a season pass (don't do subscriptions for a mainly solo game, ever, it's a terrible idea), might enable you to squeeze a bit more from this target audience, but it's not really relevant IMO.
It's about the new customers that hear about the games two year laters (or old customers that returns to the game after two years)
And they see this :
This would put off anyone from buying any game. The DLC list is larger than the game description ...
This is just telling people "you're not actually buying the full game for 40€, the full game will actually cost you 145€"
Also even though there are sales quite often, the price tag of the game or its older DLCs never changed.