This article is quoting employees conversations from 2016. It wasn't until late 2016 that Google published research on wide and deep recommender systems. I'd be interested to see if people still think behavioral data is poor and ML has not provided advances.
That said some demographics are broadly correct from behavioral tracking (e.g. a child who watches baby shark on repeat), but good luck telling the difference between a rich child and a less rich child.
That said some demographics are broadly correct from behavioral tracking (e.g. a child who watches baby shark on repeat), but good luck telling the difference between a rich child and a less rich child.