How you feed is entirely your choice, there are some excellent commercial foods on the market (ZiwiPeak for example.) In the main though, commercial dog food companies are focused more on profit than good nutrition.
Unfortunately very few vets are experts on canine nutrition, and the vast majority are sponsored by the large dog food companies to promote poor quality complete foods. In the UK most vets push Hills Science Diet, a kibble that is full of unnecessary fillers and low-quality ingredients. I wouldn't dream of feeding it to any dog, especially not a tiny Chihuahua!
There is plenty of literature explaining that wolves and domestic dogs are almost identical physiologically, and that a raw meat diet is the most natural way to feed a dog.
Here is an article you might find interesting.
anatomy of eating