Mid thigh as opposed to what? below the knee, at the hip, something else?
Blocks allow you to work on acceleration without worrying about grip fatigue being a factor in multiple rep sets. They are more convenient for rest-pause training because you are not fatiguing yourself or your grip by holding the bar for the "pause" portion. They also allow you to work on specific aspects of positioning, which can be invaluable when you are needing to relearn or mess with technique or grips.
Finally, what are the benefits of deadlifts with a pause vs. touch and go? Or better yet what are the benefits of squats from the safety pins up (concentric only)? That is not a rhetorical question. Answer that and you'll have your answer on blocks.