It seems to be "genetics are very complicated, and because many traits aren't Mendelian and polygenic additive models are oversimplified, they are useless." Mo

It seems to be "genetics are very complicated, and because many traits aren't Mendelian and polygenic additive models are oversimplified, they are useless." Mostly, it seems to copy common misconceptions about statistics. The people working with polygenic models understand that the models don't perfectly represent reality, but that doesn't make them useless! They give estimates for various traits (like height) that have been tested to correctly explain some fraction of the variance in a population. Models aren't reality, hence the name!