One of the big advantages that savers have today are open platforms (there was a time when fund managers ran their own platforms), low dealing costs, low spreads, and ETFs. All that investors need to do is just work out the asset allocation themselves and they will save huge amounts. And I would guess 95% of people reading this are able to do it.
Just to be clear, we are looking for a least bad situation. Asset allocation is very complex, there is no way most investors can get an amazing result themselves but what most investors don't know is that WealthFront have zero chance too. So the aim is to equal what they do without their mad fees (I have no idea how they charge so much, marketing? I don't know, I know small advisers that were profitable charging lower fees...it makes no sense).