Yeah, but there’s a down side (EVERYTHING has down sides!). Oval is not as strong as round shape for the same size. So they had to put more material to achieve the same strength. Otherwise, the seat post will be weaker as a result, increasing potential of broken seat post for heavier riders.

Remember way back when, bikes came with increasingly deeper dish rims? Well, they backed away from that when people got blown sideways by cross wind. Only in that case, it’s the little guys who experienced the problem the worst.