I don't think that's necessarily true. Like, yes, at the basic level, plant milk is just a mixture of plant concentrate and water, but depending on the process required to get the desired flavor and consistency, it might be more complicated than just mixing two things together. I think your premise is valid, I'm just saying that I wouldn't be surprised if plant milk from concentrate is harder to get right than having it mass manufactured in a controlled setting. With how fickle consumers are, you can't take the risk of putting out a product that isn't exactly what people are expecting. They just won't buy it. Woo capitalism, love consumer choice.