JM, putting on my nurse hat here I think you reading too much into the WebMD article. Most americans get plenty of protein. In fact most get twice the amount they need. Remember, that the recommendation is only for three ounces of meat per serving. Very few people only eat three ounces per serving. We also have other sources of protein such as eggs, nuts, beans, whole grains.
Generally, protein is not going to give you more energy in the nature of a stimulant such as caffeine. Consumed proteins function to be broken down and for needed amino acids and muscle maintaenance and replacement. Excess protein is converted over to fat for storage or carbohydrate to be consumed for energy. Between protein, fat and carbohydrates, carbs provide the most direct energy. However the recommendation is that you eat balanced meals. The Recommended Daily Allowance of protein is .08 grams per Kilogram of weight. Translated this means that a 150lb person needs about 54 grams of protein per day. Protein adds up fast. For instance, 1 egg has 6 grams. 4 ounces of chicken has about 35 grams. One-half cup of navy, pinto, black or kidney beans offers between 7 and 8 grams of protein.
Protein supplements really come into play with serious weight lifters who target 1 gram of protein per lb of body weight per day or more. Whey is an excellent source of protein although nutritionists stress that it is best to get your calories and nutrients from whole foods where possible.
The other time when supplementation is important is when you are not getting you recommended nutrients from a regular diet or if you are recovering from illness or injury. Often older people can lose their appetite, ability to chew, swallow, etc and they begin to lose weight. Here liquid supplements are helpful as they can be nutrient dense in an easy to consume form. However, even here you will not typically find just whey protein recommended. While meal replacement drinks may contain significant protein they will also contain fat and carbohydrates.