Yeah it does come across as too simple. I've heard a variation of it, also attributed to Lalane, that says, "If it comes in a wrapper, don't eat it." The idea is that if it's in a wrapper, it has preservatives added, and also sugar added to make it taste good.
In any case, it seems people love attributing quotes to Lalane!
I think people trying to give nutritional advice should just list the actual categories of food they're referring to, rather than trying to get cute. If you want to say "eat unprocessed fruit, vegetables, and meat, and avoid the rest" then just say that. To me, whenever I see somebody trying to get clever with their wording, it just comes off as moralizing. It feels like either "you should know this man-made stuff is bad for you, you idiot" or "I'm better than you because my food is 'natural.'"