We called this boil n bags in the 70s, is it for real. Their is talk of restaurants cooking this way, how everything takes hours to days. Who is going to order a steak dinner that will be ready in 2+ hours. Would not a pressure cooker give you the same results in fraction of the time. In the time of drive thru can't see this or why anyone would pay extra for a stick that does what a pot if boiling water on a stove does.
As others have mentioned, you're misunderstanding (assuming you're not just trolling). Take the steak dinner as an example.
Sous vide allows you to cook that steak to a very precise temperature, considerably in advance--even a day in advance. When you're getting toward service time, you drop the bag back into water that is a little below the target temperature, where it will sit without doing anything at all for some time.
Now somebody orders a steak. You pull a bag, dry the steak thoroughly with paper towels, season nicely, and sear it blazing hot on a grill or in a pan. You're not trying to cook the steak, just to get a great crust. As soon as that happens, the steak is ready to go, and barely needs to rest.
So while the total
time is certainly very long, the time from ordering to delivery is no longer--and probably rather shorter--than the traditional method.
So far, you might say the method is fairly pointless. But what if you could cook something completely differently? For example, if I cook slices of squash sous vide for a couple of hours at very low temperature, it will cook completely through but not fall apart. Or I could cook a very tough cut of meat--something you'd normally cook as a pot roast--for 24 or even 48 hours at a steak-type target temperature, and when I sear and slice it at the end, it'll be as tender as a filet.
Used properly, sous vide does two things: it allows you to cook things very precisely in advance and have them ready to go for service (this is mostly useful for professionals), and it creates some possibilities for cooking that simply cannot be done by almost any other means (this is useful for anyone who's interesting in creative experimentation).
What sous vide is not
is a magic bullet. It doesn't make you a better cook, and it's not good for everything. Like any other cooking method, it requires knowledge, practice, and taste.
Hope that helps.