There's no way I could eat enough protein in a day, depending on the rule you go by. I don't honestly think the average person even eats 50g a day or more, much less 150 or 200 or 250 or w/e their body weight is. Steak is about 7 g/oz, chicken's a little less, pork's somewhere in there, hamburger's slightly lower too, bacon, eggs, etc. They're all good bacon sources but whey was specifically engineered to be better and faster absorbed than protein in your diet, so IMO, it's going to be virtually impossible to match the results with a whey+exercise regime using only protein from your meals (unless you're a woman).
On average I probably eat 50g of protein a day and drink 100-150.
I didn't used to be someone who believed in supplements, either. But a doctor friend of mine is always pointing out to me (as a caution, not a recommendation of use) that supplements are
drugs, and her concern is that unlike Rx drugs, they're not required to undergo testing, so anything can be in them.
There's a study due out on Jack3d actually, they like to say there is anyway, supposed to be being published one of these days, like a university study not some 3rd rate research institution they can pay to say what they want. But they tested it against placebo and at some point it's supposed to be published.
But in general about supplements, I agree you have to know why you're taking it and what its' supposed to be doing. Some things you can't skip, or they're useless. Some things the dosage in insanely high because your body is stubborn about absorbing it. Some things work against each other (T-supps and carb blockers). I've tried lots of different ones and gotten off of some I didn't feel were doing anything. Atrophex and Epozine-O2 from BSN are two examples I didn't think did a damn thing. Axis-HT is a testosterone booster that I liked. Nitrix is a vascodillator that seems to work well. NO-Xplode, I thought was a stim, because it's a preworkout. Creatine, whey and casein are pretty textbook, doctors themselves will tell you they help build muscle. BCAA (Branched-Chain Amino Acids) are a little more fringe but lotta body builders swear by them in preworkouts, and these days they're in a lot of whey mixes.