The catechism doesn't cover much of the Catholic life that has been lost, like the May Crownings and other devotions the author mentions. A good Tridentine missal has filled out those areas for me.
I think parents were in the habit of outsourcing their faith education duties to the parish or the Catholic schools, which exacerbated the problem when those went into catechetical decline.
The Catechism covers "what the faith really teaches," as the author said. Traditional devotions can be beautiful and valuable, but they are not the Catholic Faith. And, as you point out, information on traditional devotions is also easily available, at a bookstore or library, if one is deprived of Internet access.
This is true. There's a whole culture that's just gone. The parish used to be like family. The parish where I grew in many ways still is, but it's just not the same, especially with the way people move around now.