I think we are talking about different things, aka. I'm sure we are agreed that parental or grandparental involvement in encouraging children to read for pleasure is one of the best ways to improve children's reading. Otherwise, why would schools be so concerned about small children taking "reading books" home?
I'm not disputing your superior knowledge of what "should" go on in schools with regard to reading practice. What I'm doing is trying to allay a grandparent's worries about a child's reading by suggesting tried, tested, and trusted methods at home.
The well known hact that parental involvement in education makes more difference than anything else to a child's success is not piffle. I'm sure you know that if you are/were a teacher (as I am).
Also, since my kids all turned into brilliant readers – having learned the basics before they ever went to school (no, I'm not talking about learning the alphabet, but about other reading skills) – clearly what I and their fathers did with them is not piffle either.
So, I repeat for worried GPs, Keep Calm and Carry on Reading For Pleasure with your GCs. Any child who grows up knowing that reading is for pleasure and well as being useful cannot go far wrong unless they have a specific learning difficulty, but that's a separate issue from this discussion.
And if you're still worried, talk to the child's teacher.