“Necessary?” Generally speaking NO. I just sat in on a webinar on this very subject. The speaker was Nancy Clark a renowned sports nutritionist and author. The gist of the webinar was that in most (if not all) cases, an “engineered” recovery meal or snack (which would include manufactured recovery beverages) are NOT necessary. What is necessary (or at least highly recommended) in the case of high-intensity, or long endurance workouts or competitions is that some sort of a recovery snack or meal is taken in.
While not “necessary,” of course, what is important after a high-intensity workout or competition is that you intake a recovery snack or meal that does the job. As Ms. Clark recommended, a combination of a carbohydrate for replenishing the depleted glycogen stores, and protein for repair to the muscles. The bottom-line is that whatever recovery snack or meal that a person takes in is entirely up to them (it’s more a matter of taste, and budget) – whether it is a commercial recovery drink, manufactured recovery snack, or actual food intended to enhance recovery. What’s most important is that they intake something to aid in recovery from their high-intensity workout.
I hope this helps.