More of a, "i wonder what would happen" kinda thing. Stomach is designed for breaking down food step by step, skipping steps i guess limits intake of certain nutrients. I know fibre is released in certain ways from breakdown of food, not sure on the actual specifics of it, fibre vs sugar intake, aka fruit smoothies.
Taking a browse through the ingredients and nutrients, as well as other powder things, (Huel makes protein powders look horrendous, first ingredient being thickener, wut), i imagine you could make up some Huel very cheap. Getting clean powder protein source might be expensive-ish, i haven't looked though. The vitamins can easily be replaced with vitamin tablets. You could get pretty adventurous, and play about with ingredients. Actually, Lentils would be a good addition on a quick scour, i know they come in dried or ready to go tins... And lentils are nice anyway. Nuts are expensive, if you want the low fat ones IIRC. Honey is a good source of natural sweetener, obviously. I suppose the super lazy could just go trail mix, lentils, vit tabs, honey. The lentils can stay in fridge, the rest blended ready to roll. I wouldn't be surprised if you could buy certain sweetners to aid the honey, but then you'd be adding sweetner...
I don't understand why their bars are still terrible though. Decent sport bars are far and few between. Vegan ones are non-existent in shops also.