I feel like nobody in this thread has made a cake before and thinks it's trivial to do, and boxed mixes are just premeasured flour, baking soda, and sugar.
The other issue the article's author doesn't discuss is that boxed mixes are usually country specific. What you find in the US is usually not available in 90% of the world, nevermind in the right box size.
Bread is a lot more difficult due to kneeding and shaping which are skills that must be honed.
Cakes, on the other hand, are just mixing and pouring which any idiot can do. The only real variable is the flour so some recipes might work better in your region than others, but cakes are still much more forgiving than bread (flour is more than half of bread by weight, but often less than a third of a cake).