Yes, as I'm now being trained to do general surgery myself, I can tell you the reason for the change too. Back in the day it was thought that making someone rest would increase the healing, reduce the risk of sutures failing, and also, because you could then fast for a longer period, would reduce the need for bowels to open etc thereby reducing infection risk.
I recent years most of this however was found to be decisively false. In fact gentle exercise gets the heart working and thus improves circulation and perfusion of the wound which in turn speeds healing. Improved suturing techniques using vycril and monocryl disolvable sutures, and in some places staples, has also vastly reduced the risk of suture failure and thus it is also safe. Clearly you dont want someone doing a marathon, but there have been very convincing clinical trials, which showed consistently better results from earlier mobilisation and good nutrition, and in fact so much so that the much much faster healing actually reduced the infection risk by far more than avoiding the need for bowel movements.
All of this also vastly reduces the risk of serious complications like DVT... so its actually a no brainer. While you dont want someone straining, the faster you can get them mobile and back to normal the better for them.
The result of this is that these days they get you in, prep you, operate the same day, and get up and out within three or four, and you get better healing a nd afr fewer complications than us oldtimers who had the seven days (or six).