I think you are overestimating how good he is. Pujols consistently put up >8 bwar seasons from age 23-25. Soto has a high water mark of 7.9 this year following two years of 5.5. He simply doesn't have the hit tool nor the power tool either Thomas or Pujols had (at least not consistently). You need to get major value in the early years to make Soto's later years not extremely painful (Let's be honest, this is likely a 13 year contract). I'm not sure that value exists at 600-700 million unless you get 2020-2021 Soto but that's the outlier right now.
Even at $10mil/WAR, Pujols 26-35 is only worth $517 million. I just can't how anyone justifies $700 million...Ohtani at least had the Japan marketing bonus (imagine how may sportsnetNow subs rogers would have sold). Yes, 1 WAR going from 8 to 9 is extremely more valuable than going from 1 to 2 but I'm not sure we ever see Soto at 9 plus WAR.