just as there's no evidence that your current diet ... provides everything you need to be healthy
Yes there is; my continued survival, my avoidance of hospital, my ability to heal wounds and recover from illness...
You're right, of course, that there is evidence from experience, and other comments discuss the extrapolation of such evidence to Soylent, both for and against its risk to health.
I mean rather to address the calls for randomized, controlled experiments. Indeed, I would like to see a rigorous clinical study of Soylent, and I would not believe any specific claim about the health benefits of Soylent without at least that much evidence.
But the standard employed by most people for making dietary changes, even major ones (e.g., any fad diet), is basically whim a...
Rob Rhinehart's food replacement Soylent now has a crowdfunding campaign.
If you're interested in one or more of these benefits, send in some money! There is also a new blog post.