Natural doesn't mean safe, and artificial doesn't mean unsafe. Yes, it's a good rule of thumb to eat foods in their most natural forms (in most cases), but there are many notable exceptions.
There are many foods that are unsafe (in some cases toxic) in their most "natural" forms. Acorns, legumes, potatoes, eggplant, taro.... must be cooked to remove the toxins.
Cooking is a form of processing (though a low-level one).
Many entirely natural herbs are highly poisonous, and many foods that people have eaten for thousands (if not millions) of years have toxic effects despite their "natural" origins.
Mustard oil for example is banned for edible consumption in the EU, USA and Canada, because of its erucic acid content. The USFDA requires all mustard oil to be labelled "For External Use Only", because erucic acid is known to cause accumulation of triglycerides in the heart; development of fibriotic lesions of the heart; increase in risk of lung cancer; and anaemia.
Legumes and grains contain "anti-nutrients" that actually leach other nutrients from the body.
There are countless other examples in which "natural" foods that humans have eaten for centuries (or longer) have potentially deadly consequences if eaten in excess (and excess is pretty much determined by whether or not a person experiences those consequences).
In some ways "artificial" ingredients can be safer than natural ones, because in the USA an artificial ingredient must be proven safe before it can enter the marketplace, while an herbal product has to be proven unsafe (and usually VERY unsafe) before it can be taken off the market.
That doesn't mean artificial foods are better than natural foods, but it also doesn't mean that any artificial food is inherently less safe just because it's not natural.
It's human nature though to want simplified "rules" to live by, because it's easier and more convenient to apply to real life situations than it is to research each food/substance before purchasing and using.
It's ironic that people are more concerned with food safety than with environmental toxins which present a much larger health threat. Eating a pound of aspartame a day is probably safer than living in a modern home, using ordinary household chemicals (natural and manmade) and using ordinary cosmetics and fragrances.
It's human nature (probably biologically hard-wired) to be concerned with food (because it's something we have complete control over) and yet to be unconcerned with the deadly natural and artificial chemicals that we live with every day.
Cleaning up my diet has had very impressive health benefits, but not nearly as impressive (by far) as has eliminating environmental toxins (many considered "safe" only because they've been in use for hundreds of years, such as ammonia, which is a natural substance, derived from animal urine, and it's extremely harmful to the lungs).
I was diagnosed with asthma on the verge of copd and had a mystery autoimmune disease damaging my joints, skin, nose cartilage, and lungs...
Removing environmental irritants (natural and artificial) and seeing such dramatic health improvements got me very interested in environmental contaminants, and I was shocked at how many carcinogens and other unhealthy substances we live with every day, without a clue (and which no one seems to be concerned with except a few extremist researchers and "health nuts").
And these substances are KNOWN to cause severe health effects, and yet no one seems to notice or care, because of the perceived "need" for sofa cushions, insulation, fragrances, cosmetics, laundry softeners, oven cleaners....
It's hard to wrap our minds around the fact though that stuff we live with and put on our skin can be more dangerous than what we put in our mouths, so people will continue to obsess over the safety of a food additive and ignore potential carcinogens and poisons because we're not ingesting them (only we are, because we're inhaling the toxins or absorbing them through our skin).
Researching the potential dangers of foods, household products, cosmetics, fragrances... is time consuming, frightening, and overwhelming (you can't avoid everything that's harmful so where do you start and what's most important?), and so most people avoid the information seeking entirely and instead rely on common media and word-of-mouth (without verifying the reputation or truthfulness of their sources) and grossly simplified guidelines they can apply to their life... such as "natural" vs. "artificial."
If you aren't able or willing to do the information-gathering and fact-checking, then these oversimplified guidelines probably are better than nothing. Most natural foods probably are better than most artificial ones, especially if you're eating a wide variety, but it concerns me that as a nation, we're all very concerned about what we're eating (which is good, although much of what we think we know about nutrition is wrong), and yet generally we have virtually no awareness of much more dangerous toxins we're exposing ourselves and our children to because we're not aware of any danger whatsoever.
And what concerns me the most is that many of these toxins and dangers are coming from products we're using in an effort to make our environment "safer" when we're actually doing the opposite when we're using household cleaners, fragrances, skin-care products, and sanitizers).