There's a marked difference between all of the above if you take a cursory glance at the nutritional information. If you tried to eat a 2,000 calorie diet on classic Slim Fast, you'd be getting around 200 grams of sugar and over twice the recommended daily allowance of sodium. Ensure, Cliff Bars and a lot of other popular snacks of that kind compared about as unfavorably last time I checked.

I agree with the common sentiment that Soylent's original goal/purpose - a simple powder/drink that could serve as one's sole source of nutrition - is sort of ridiculous, but it actually led to a remarkably well balanced product unlike anything on the mass market. It's remarkably filling and nutritionally well balanced for a convenience food.