I hate Soylent so much. If you like the idea of eating efficiently, just get some whey protein and possibly a veggie shake mix. Oh wait, that's not good enough. I need to seem hip, cool, and into the latest fad diet plan.
By contrast, replacing a full meal with whey protein takes a stance on what you should and shouldn't be eating vs general dieticians' recommendations (and the FDA's). I wouldn't recommend replacing most meals with either one, but if I had to pick the fad diet, it'd be whey.
Marketing 101: make people believe there's something wrong with what they are doing, then sell them the solution.
It's more complicated. Hate is a strong word already. I don't think anyone (okay maybe a very tiny minority in sv or something where cool is defined differently from everywhere else) drinking soylent is trying to be hip or cool.
Do you hate people trying paleo diets? How about gluten free? I doubt it.
Pretty much any of either that is on the market. Soylent isn't that remarkable, nor is there a well-understood narrow optimum (despite Soylent both pretending that there is and that it is always right at that point even with the major formula changes.)
> Do I need to buy a blender?
No, just a closed container for shaking will work tolerably well, or a blender bottle/cup (the ones with either an agitator ball or internal fixed plastic blades to help with shaking a powder) is even better.
It is in no way an equivalent to Soylent or other nutritionally-complete products, because it's not nutritionally complete.
Their purposes are different. Whey protein is great if you need to bump up your protein intake in a really convenient fashion. Soylent and friends are great if you need to get a balanced meal in a really convenient fashion.