Reverse cooking helps facilitate the maillard reaction. You get a better sear on meat cooked as the OP describes than you do with a raw cut cooked "the normal" way.

The low/slow process is so your able to lightly cook the exterior of the meat so you can get the subsequently perfect sear in the cast iron afterwards without overcooking your steak internally.

The "normal" way takes longer per side to achieve the same amount of sear, which then CAN lead to overcooking, especially on thinner cuts of meat.

The reverse sear is more about a perfect sear than the tenderness. You could sous vide as well to achieve the initial cook, followed by a sear... but who tf has a sous vide machine vs an oven lol (although a sous vide would allow for more precise temp control)

You could also achieve a good sear without overcooking by freezing your steak, thawing it so the exterior is softened but the interior is still slightly frozen. This let's you do a hard sear on both sides without worrying about overcooking the center.

Both the freezing technique and the reverse sear technique require solid experience though if you want your steak done to your preferred doneness... reverse sear could cause an overcook, and freezing could cause an undercook if you dont use a meat thermometer, or at least have the experience to cook meats "by touch"