Digital intimacy ruins the appetite for the real thing. So, when kids are gaming or even when spouses are gaming, they lose their appetite for genuine intimacy. Kids lose their appetite for getting their intimacy needs, their hunger for significance and attachment, with the family, and it erodes the relationship between them and their parents.
Peer attachments are not the problem themselves. It's when they compete with adult attachments that the problems emerge. It's just like when siblings get attached to each other. If they start revolving around each other, then the parents can't do anything with them because it's a competing attachment.