I guess what I am saying- is that you are not stating facts.
You stated " the slowly, slowly approach is a thing of the past." and "the entire new curriculum places an entirely different set of values and reporting criteria for what was the traditionally play based prep year"
Your understanding of the review of the curriculum does not reflect what the document actually says. They still support following an individual child's interests and learning pace. They support learning through play and no where in there does it state that they will be introducing formalised teaching instruction.
To the OP- , in the UK (where I teach currently-I was previously teaching in NZ) they begin introducing literacy concepts at age 4, but it is still in a play based approach (EYFS) Through singing, songs, games. As the children get older they gradually introduce more formal instruction. The arguments for a play based approach to every aspect of learning is so that children are learning about everything all of the time, and at the time most appropriate for them.
For example- a child might love the home corner and playing 'Mums'. So the most appropriate introduction to literacy teaching for her might start with adding a phone and notebook, a calendar & pencils, adding books to read her baby stories.
We might change the home corner into a hospital for a few days, add prescription pads and hospital signs. We might create a shop and ask her for help to make price tags and money, information about what we sell. The resources help create 'teachable moments' then as the adults observe how she uses them they scaffold her learning as she uses it. Providing enough support to allow her to make some discoveries independently, giving enough information and feedback to spark further interest or achieve something exciting. "Thanks for making the sign for our shop Sophie- Mary & Jo come to our shop, Sophie has made the sign that tells us we are open" So not only is it teaching her about literacy, she will have opportunity to use her imagination, develop social skills, potentially math concepts and independence.
Next time Sophie is in a shop with her Mum she might spot a sign that says open/closed. So the journey to becoming a competent reader begins.
vs
Formalised learning which might consist of plenty of sitting still, being quiet, following what the adult wants to do, rote learning, repeating sounds or completing worksheets. Some of limitations of this approach is that it has no context, it assumes all children learn the same thing at the same time in the same way, they are only learning one concept at a time, and most importantly it is BORING (not many children rush to the table for worksheet time)- so it is creating an unnecessary hurdle between the child & learning. If we want to raise robots or factory workers then the earlier the better for this approach. However most people want happy, self motivated learners who can think critically, communicate effectively, make friends and are literate.