Recommended system requirements (Rise of the Tomb Raider)

What is the recommended little system and why they are not specified in the Incentive? There is only a minimal but why? For Each game published the minimum and recommended system requirements, why can't I learn PC what configuration is needed to recommended? Wanted to buy the Incentive game but stopped because of the lack of recommended sistemok. And suddenly there gtx 970 why I'm such a game? When will publish the recommended to rise of the tomb rider?