You'll often find such mealy-mouthed conclusions in write-ups of studies where the evidence doesn't confirm the author's hypothesis, and especially in anticipation of controversy. (in this case, your quote doesn't come from a study author, I guess)

If there's no benefit on average, then there's no reason to recommend on average (disclaimer: I take a chewy multivitamin because I remember being convinced by evidence that manganese is a bad thing to supplement, and most multivitamins have 2mg of it).