All she is saying is that this is the way reading develops and we should be doing the same for children. Reading a challenging book every now and then is ok but they are unlikely to develop a love of reading if reading is always challenging as opposed to relaxing and fun. Most of the peer reviewed research agrees with what the teacher in the article is stating. I think the point is as long as reading is developing in a typical manner there is no evidence that an early reader will be a better reader in the long run and much of the research being done at this time indicates that she is right.
Reading doesn't develop the same way in every child. It developed differently in all three of my kids, for example, and differently again in my neighbor's kids. Like linear growth, there are overall patterns, but few kids fit them exactly and many are way outside the bounds.
I agree with your note about not being made to read reading challenging books too frequently.
But "challenging" has to be defined by the person doing the reading, not a teacher who decided that Harry Potter is too hard for a given age group. Don't forget that being made to constantly read books that are too easy can also be detrimental.
