The article states that scrotum and testes development is the analogous measure for males.
The focus of the article is not on hidden indicators of sexual development, but on the social indicators that are visible despite clothing.
A girl with breasts becomes a sexual object to many boys and men. The attraction they show to her can be extremely disrespectful. She might become an object of derision to girls if she precedes them in development.
A boy who is tall, broad-chested and deep-voiced gains status among boys. He is a more formidable athlete and competitor. Girls may admire him and be attracted to him, but they generally don’t isolate his parts and turn him into a piece of meat.
OK. But anyhow, normally these don’t become social factors.