Example:
Two guys run 28:1 final gear reduction. One guy does it using 4.56 ring and pinion and the other guy does it using 3.73 ring and pinion (obviously they are using different tranny and t-case gearing). The guy running 4.56's is less likely to twist his driveshaft. I don't know if that plays into running direct drive vs a lower gear in the tranny or not......
....but more likely to strip the teeth off the ring gear. It's torque being displaced to different parts of the drivetrain. With 3.73's, the ring gear will have more materiel for each tooth, less likely to rip them, thus the driveshaft twists, u join pops, etc.
The drive line parts listed here are just examples. It could be any part of ones setup that goes, all based on which parts are gonna be stronger with the amount of power placed against them.
You're right about final gear ratio, doesn't matter how you get there, 1:1 is still 1:1. Like bullfrog said, its about wheel speed. The faster the tires are turning, the quicker you can build up groundspeed and the more momentum the trucks gonna have before the sled drags it down.