That's true enough, but by far the majority of advertising of food products that kids are exposed to comes through television. Now don't get me wrong; I'm not advocating for a TV-free household, but with the statistics they cited with kids seeing, on average, 10,000 TV commercials (if I remember correctly) for food products every year I found myself wondering how much TV those kids were watching. I think I remember reading somewhere that the average child watches something like 3-4 hours of TV per day. Reducing the number of hours that your kids spend in front of the TV set can only be beneficial on a whole range of levels, all the way from increased activity to more time spent actually reading a book or spending time together as a family (we have a family game night once a week) while reducing the number of commercials that they are being bombarded with at the same time.
I've also fallen prey to the "Please can I have some sugar-bomb cereal? Please? Please? Pleeeeaassseee??? But I worked out a compromise with my 2 girls on that. They get to pick one box or bag of cereal each month and when it's gone, it's gone. No more until the next month. Same thing with other treats like candy and ice cream. I don't always say no, but I try to keep stuff like that limited to once a week.