Why YSK: When you cook meat, any water on the surface must first evaporate before much browning can occur. You want to get as much of a Maillard reaction as possible in the limited cooking time you have before the meat reaches the correct internal temperature. Removing the moisture first means that the heat of the cooking surface isn’t wasted on evaporation and can instead interact with the meat to form the complex sugars and proteins of the Maillard reaction.
Generally no. Ground beef doesn’t have a “surface” the same way a cut off meat does. As meat cooks fibers (can’t remember if it’s the muscle of the protein fibers specifically) contract and squeeze out water. In ground beef the water will be escaping every which way. In a cut of meat more of that water has a better chance of staying within the piece.