This is a normal way for F2P games to make money - to either make the content, that you need to grind, available instantly for money or to speed up getting this content for money. And it’s fine, as long as it is accessible to the regular non-paying player in a reasonable amount of time. And that’s the big issue here - top tier vehicles are not available in a reasonable amount of time. You literally need to spend hundreds of hours just for a single tree (TREE, not even a COUNTRY). And even then you probably take shortcuts by, for example, not researching one of the branches.
The difference here is that in CS and Fortnine you have everything that is important to gameplay available for everyone equally. And the main selling point of those games is different. One of War Thunder main selling point is a huge number of realistic-ish vehicles. And guess what, you won’t be able to experience most of those vehicles EVEN IF you buy premiums. And when you have a lot of potential options on what you “can” play, and meanwhile you spend dozens of hours in the same vehicles, it becomes boring and repetitive.
Also, returning to your examples - you don’t need to pay anything to play Fortnine. And yet people still spend LOTS of money just on cosmetics. Same goes for CS (apart from buying the game itself). That’s what happens when the game is actually fun and enjoyable for most players most of the time, which war thunder honestly lacks.
In order to make war thunder work with pay to play model, you need to significantly change how the game works. Probably to the point where it won’t be the same game anymore. Grind is not always bad, but it needs to be done right