I'm not sure what play groups have to do with phones. Perhaps I misunderstand the purpose, I thought the play group was to get children together for their own entertainment.
And it's perfectly possible to be near your child with your nose buried in a book or a magazine.
I think he means play groups for infants and toddlers younger than elementary school age - before they have the ability to develop friendships on their own in school and so forth.
And it's perfectly possible to be near your child with your nose buried in a book or a magazine.