Reading isn't natural. It needs taught.
Here's what Sebastian Wren [an elementary school reading expert] said: "Despite our best educational efforts, approximately 40% of our 4th graders lack even the most basic reading skills. These staggering numbers provide evidence that reading is a skill that is quite unnatural and very difficult to learn."
Try this idea on: Perhaps it isn't reading that's unnatural but that reading at 9 is not universally natural? (Lots of unschooled kids would be "statistics" in school.) Or learning to read after years of pressure before they're ready to read makes learning to read exceptionally difficult?
Wren has confused "helping kids to read" with "preventing adult illiteracy." The goals aren't the same at all. It's not his job to figure out the best way to help kids to read. It's his job to identify indicators that might lead to adult illiteracy. It isn't his job to figure out if the "problems" he sees are actually related to adult illiteracy. It isn't his job to figure out how kids naturally learn to read. It's his job to figure out how to get them to read in school.
40% of 4th graders lacking basic reading skills is a frightening statistic for schools who base their curriculum on children reading independently by 4th grade. But does it mean anything for kids who aren't in school? And if lacking basic reading skills in 4th grade has a high correlation with low reading skills as an adult, is it because the skills weren't acquired early enough or because the environment of school was demoralizing for learning to read after that point?
There is nothing natural about reading; it is very much a cultural construct.
Spoken language is a cultural construct too. What part does its "unnaturalness" play in learning to speak? Having language available and useful is all that's necessary to learn it.
The issue with reading, though, is that there is a right way to do it within the context of the proper grammatical use of the language.
The same is true of spoken language. But what barrier or stumbling block is that to picking up our native language starting as toddlers?
When reading instruction happens or should happen, THAT is what is open to debate.
And the reasons people debate teaching kids to read is:
Most people lack experience with kids learning to read without instruction. They can't realize that kids do learn to read when given the freedom to do so. They're caught in the "Well, maybe that's true, but I want to be sure" mode of thinking.
Their goals are different. Someone whose goals are to allow learning to unfold naturally isn't going to have the same needs as someone who wants to "make sure" or someone (like schools) whose goal is to have the kids reading independently by a certain age. This argument is like two people debating what it's best to pack for a hike when they don't realize one is planning on hiking across the desert and the other is planning to hike Mt. Everest. Parents' true goals are masked by thinking their goal is to do what's best for their kids, not realizing they aren't defining "what's best" in the same way. And often they aren't defining it the same way because of fear and ignorance of how children really learn when given the freedom to learn what they want when they want it.
So what is necessary for children to learn how to read?
Wren seemed to be asking the same question. But he wasn't. He was asking "What is necessary for children to learn to read in school?" The environment in school is different than an unschooling home. The goals are different. That all affects what the child needs. Debating what school kids needs is beyond the purpose of this list and probably an exercise in futility considering all the educator hours that have been devoted to it for 30 or more years! ;-)