My writers have personal word books (a.k.a. dictionaries first grade style), but they don't know it. I also have about 8 hardbound dictionaries in my room. They don't know about those either. These resources are a mystery to them for the very reasons Regie explained in the quote above.
1. "Their free flow of thinking and writing is interrupted." From day one my writers have to learn that spelling is not what dictates content. If they only write what they can spell or can easily find in a word book, their writing will not live up to its potential. It will sound stilted and lack any kind of detail.
2. "Over concern about correctness while composing slows writers down." I keep the word books a secret for as long as I possibly can, but once they come out of hiding, writers want to use them for every other word and the quantity of writing considerably decreases.
3. "Another reason to put aside resources, at first, is to encourage students to figure out spellings and choice of words on their own." The writers in my room have no choice but to be risk takers. They know what I'll say if they ask me how to spell a word. "If you can say it, you can write it." They must develop the phonemic awareness skill of hearing sounds in words. The skill won't develop if they have a word book in their lap on day one or even day fifty.
I don't mean to imply that spelling resources are evil. There's a word wall in my room that we use daily, and my writers have personal word walls in their writing folders that they refer to. I just believe that word books and dictionaries need to be used wisely. If not, they can get in the way of the writer and their writing.