WHY does meat have to "rest" after cooking? ?

All meat should "rest" after cooking: at least 10 minutes for small pieces and 15-20 minutes for large pieces, such as chicken baked whole. Why is this so important?
?
As the juice of just cooked meat is too liquid. If you cut the meat, it will leak out, leaving the piece too dry. The "resting" time allows the juice to spread evenly over the meat fibers and thicken, making the meat tender, juicy and flavorful.