Not necessarily even 'all the time'. Just substituting for any meal that wasn't above average in terms of quality would be nice (health benefits, saved time, probably additional second-order effects).

The benefit versus traditional dietary supplements is explicit design for consumption in isolation. (That's ignoring all of the unfortunate experimental errors observed here, of course.) There are medical products that fit that bill, but they aren't marketed towards consumers and are therefore much more expensive (if purchasable at all).