It's true that today most OMS, for most procedures, for most patients will no longer need to wire the jaws, but it's not unheard of, and there are some particular types of orthognathic surgery that still require it always. However, knowing that most patients would prefer to avoid being wired shut if possible, it is common for an OMS to offer an alternative procedure.
The reason that most orthognathic surgeries no longer require the jaw to be wired is nothing to do with the post-op elastics really, but is due to the development and use of rigid internal fixation - miniature plates and screws (usually, but not always made from titanium) that hold the bones in place while they heal.
The elastics that are sometimes used in the immediate days and weeks post-op are usually there to help train the jaw muscles to relax in their new positions. Sometimes the OMS will also have the patient continue to wear a splint for some period of time following surgery - the splint is attached either to the archwire (via surgical hooks) or directly to the brackets, so not everyone needs surgical hooks to be added to their braces. Lingual patients usually need buttons added on the labio-buccal side (the "outside"
) of their teeth for the splints and elastics.
Recovery is a very individual thing, and depends partly on the length of the surgery - this in turn depends on the skill of the OMS and also on what orthognathic procedures are involved. Age, and general health play into it too, as does your level of activity post-op - mild exercise is to be encouraged, so take the dog for a walk, if you have one
Nutrition is also extremely important, and unless the patient is wired shut, it should be possible to manage a diet that offers all the necessary nutrition, and in sufficient quantities to make weight loss minimal. Depending on the OMS and the procedures performed, the patient may be back to chewing soft foods in under a week, and many people can be back to work within as little as a couple of weeks.