While many of these reasons make sense, there are a few points to consider that might steer you away from rice cereal as a first food:
1. Rice cereal is a simple carbohydrate and as such it spikes your baby's blood sugar, without offering much by way of nutrition.
2. It is a processed food and in general, almost every doctor out there recommends NOT to give babies processed foods, especially at first. Processed foods are not as healthy as whole foods, like fruits, vegetables, and well sourced meats.
3. While babies will accept almost any food you give them at first, toddlers and school age children are significnatly more likely to be picky eaters. If you have a picky eater on your hands, you can confirm that picky eating children almost across the board love carbohydrates (cookies, crackers, pasta, rice) but generally refuse veggies and protiens. Since we don't really need to worry about kids learning to eat carb, why start with a simple carb as the very first solid food they ever eat? This may lay down a foundation for a lifetime love of simple, processed carbohydrates.
4. Breast milk and formula are high in protein and fat so this is what your baby's stomach is used to processing. Some argue that your baby's body doesn't even produce the enzyme necessary to properly breakdown carbohydrates at 4-6 months. This causes foods like rice cereal to be hard on your baby's stomach.
5. There are other foods besides rice cereal that naturally offer iron in higher amounts and in a more easily absorbable form.
6. Arsenic (a known carcinogen and poison) has been reportedly found in commercially available rice cereal in 2012.
7. If you follow the AAP recommendation to start solids at or around 6 months, your baby most likely has mature enough gross motor and oral motor skills to eat a wide variety of foods.
8. Ask any pediatrician or infant feeding specialist: the whole point of those first few months of transitioning to solids is oral exploration and play with motor pattern learning. Rice cereal offers very little in terms of sensory input and doesn't challenge developing oral motor skills. It is so easily ingested it hijacks the focus from play and exploration and puts it on intake and quantity.
9. Looking again towards toddlerhood- It takes very minimal oral motor coordination to eat things like crackers, cookies, and processed meats (I.E. chicken nuggets). It takes mature and strong oral motor skills to eat resistive foods such as raw and even partially cooked veggies and fruits, nuts, and baked or grilled meats. Building strong oral motor patterns in a safe way, from a young age (before food refusal sets in- around toddlerhood) is crucial to your child accepting these foods when he or she is older. Once he or she hits those toddler years, there is almost always less interest in exploring new foods and practicing how to eat them. If your child doesn't know how to safely eat resistive foods by toddlerhood, she or he will most likely refuse them completely for years to come- until they grow out of their resistant phase. I'm not suggesting you give choking hazards to your baby, but I am suggesting again that rice cereal does almost nothing to advance oral motor patterns. There are other first food choices that do provide safe opportunities for oral motor skill advancement.
If any of these points ring true to you or concern you, I suggest doing your own research and discussing with your baby's pediatrician before deciding what to give your baby for his/her first solid foods.