You need strength to be powerful, but if your rate of force development is fast enough, and your Index of explosive strength is low enough, you don't need it as much. This machine looks cool, but how is it all that different from a seated double leg press machine? When during running do you put force on the knee/hip joint at 120-90 degrees? Or put force on the knee at an angle greater than 15 degrees? And when do you move this slowly through your motion of running?
You're right, it hits a lot of the muscles that running does, but not all of them, and it does so in a very different way than running does. It can be helpful, but it's a stretch to call it the most specific weight training you can get. Otherwise you can argue that distance running is specific to vaulting because aerobic capacity helps increase anaerobic capacity which helps increase your ability to sustain ATP-CP capacity, which is what vaulting uses. In the same way, this machine works the muscles of running at a large joint angle which increases your ability to increase force at smaller joint angles which increases your ability to produce power at these smaller joint angles.
The "most specific" training for sprinting is sprinting, and for weight training, any olympic lift will be more specific to sprinting than a lift where power is not a factor. Just be careful with the term specific, it would be better to say "appropriate" for an early season weight training cycle.
The greater the challenge, the more glorious the triumph