We were probably a little more aggressive than most people with introducing foods than other people (even typical people), but I got the impression from the doc that we were seeing at the time that it as much a result of eating a more varied diet as it was intentional. He started eating nuts (as peanut and other nut butters mixed into baby cereal) somewhere around 5 months. (And we kept it up, mainly because he really does not like bland food. Weird baby.) Hard boiled eggs and soft cheese were some of his first 'pick up' foods. He was eating shrimp and other shellfish at 9 months. But who knows if it helped - maybe he will still have food allergies eventually - mine were adult onset (though I did have symptoms to a few as a teenager) and are mostly weird.
My brother and I were both formula-fed, though I had breast milk for a bit as a baby. He developed a corn allergy at 2 or 3 - I'm sure his formula had corn in it. I was on soy formula and am allergic to soy now. But we also grew up in the middle of nowhere surrounded by corn and soy fields, drove around these places frequently with open windows during harvest, and played out at the remote location of my grandma's business, which involved farming support (anhydrous ammonia) and was surrounded by fields.
I won't be giving new baby a packet full of 9 different powdered allergens. From what I have seen, the science is barely there on peanut, and isn't there at all as far as I know for other allergens. If the child has a reaction, then you have to consider whether it is one of the 9 things in the packet, plus however many ingredients in whatever you mixed it into.
Places like Israel, where peanut based foods are more common for young kids (though DS only loves the Strawberry bamba) have fewer peanut allergies. But what if all we end up doing with these 'prevention' products is creating a new most prevalent allergen. Non top eight allergies suck. Labeling is better than what it used to be, but it is not awesome.