Was he just setting them in a few inches of dirt or what? I mean, I learned the hard way too when a storm took out my first attempt at a fence. For any fence, you really need to go at least a third of the post height underground, even for short ones. Otherwise, the leverage from the wind will just rock it loose over time, idk why people skip that step. It's not just about falling over immediately, but the posts will start leaning and the whole thing gets wobbly. Taking the extra time to dig proper holes and maybe even set them in concrete is way cheaper than replacing the whole fence later.