You are correct that soy bean protein is complete and the protein is of high quality, but it's a pet peeve of mine when people talk about protein completeness, as it is essentially false dichotomy. There is a (multi-dimensional) continuum of protein completeness in the sense that the amino acid profile doesn't just have to contain every essential amino acid, but has to contain it in the right amount, as is required by the average human being.

Soy protein for example is particularly low in Methionine and Cystine. If your goal is to get enough of those, you might have to eat three times as much soy as for example egg whites (by weight). But similarly soy protein has more Tryptophan than beef. "Completeness" is a binary that is not quite sufficient to describe protein quality.

There is a reason whey and egg proteins are more popular among strength athletes for example, as they are richer in leucine, which seems to be the limiting amino acid in muscle building.

I still think we should eat way less meat and soy is a very high quality substitute for it.