I am not sure this is fully correct....
For light and stable winds, yes a small front wing is no good as you will never get up.
But when you get a smaller and much faster front wing up foiling, it will ride so much faster, that you will get even more lift and power both from your front wing and you wing-wing
So if wing is a bit gusty, a small front wing can sometimes be great.
It is not that black and white.
Many drop the big beginner front wings because once they get up, they dont go any faster, so you dont gain lift nor power, like with faster wings, besides being impossible to ride waves as they glide too slow.
It is true though, that in marginal conditions where difficult to pump up on foil, a bigger wing is great for this very purpose, eventhough they turn lousy.