If I'm carrying a stove, then I'm carrying fuel too. That weight and space adds up. Even if I'm carrying my MSR Windburner, it's still about the size of my first aid kit. My old MSR PocketRocket was smaller by itself, but required a mess kit or a pot of some kind for the hot water. I could go with a soda can alcohol stove, but then if I spill my fuel I'm a bit boned and they aren't always the most reliable or efficient setups to begin with.
Soylent is: remove Soylent package from pack, dump approx 10 oz into Nalgene, add water (cold, filtered from a stream if possible), shake, and continue.
Cooking while backpacking is fun ... sometimes. Once in a while it's nice to take the time to put together some backcountry gourmet stuff.
But for just having the equivalent of emergency rations in my pack, Soylent really is better than the other choices.
Oh, and anecdotally: digestion is a pretty big deal when you get far enough away from civilization. I've had some Mountain House meals do some pretty unhappy things in my gut, and there's only so much cleanup that small wad of "oh-no" TP I carry around can do. Soylent tends to digest really well and not cause post-digestive messes. Unless, of course, you happen to be one of those many people who were allergic to one of their recent formulations.
