When I started Argentine Tango in 1995, my first teacher told us that we didn't need to use our arms and hands to lead, just the chest. He demonstrated by dancing around without using an embrace. We took this to heart, and copied him.
When I first went to Argentina in 1999, I noticed that a lot of the older milongueros DID use their hands and arms to lead me. When I asked some of the nuevo tango folks with whom I was studying whether this was right, they said the older guys didn't have good technique--and that's why they used their hands to help lead. I enjoyed following the older guys, and switched to going to afternoon milongas on my third visit to Buenos Aires, in order to dance with the older generation, but I didn't change much about how I led. It's funny that I didn't make any connection between the ease of following them and their technique!
I started studying with Oscar Mandagaran in 2000 while in Buenos Aires. He advocated an embrace that used chest, arms and hands as a unit, the "marca," to lead ("la marca" means "the lead"). However, it wasn't until 2008 that I converted to teaching people how to use the entire body to lead, not just the chest. When I organized for him and Georgina Vargas in the USA, he took me aside and demonstrated how much easier it was to follow complex moves if he helped me with a clear marca, rather than just moving his chest. The difference was so clear that I had to start relearning tango to dance better.
As a follower, I am sold on this precision that allows me to "let myself be led" rather than trying to figure out what the leader MIGHT want me to do. As a leader, I like having the ability to help the follower arrive at the same place I do, with less work. To quote Oscar, "You don't want to use your hands and arms? Fine! Keep doing your four or five moves! If you want to do more, you need to help the woman understand what you want her to do!" There is a delicacy and a sublety about this way of leading that appeals to me, because it allows the fine details of tango music to come out, along with the improved connection between the dancers.
While new leaders (or leaders new to using this method of leading) can sometimes feel like the scarecrow in the Wizard of Oz, pointing several directions at once, the end result is worth waiting for! It takes a while to figure out how to use the hands and arms to HELP the torso lead, rather than to have them take over, which is NOT a good marca. For those of you who are sure I am wrong, don't knock it until you give it a fair trial!