An ideal text, according to Newkirk, is the text which a teacher/tutor/consultant has in their mind during a writing conference with a student; "an image of the true version which this paper [the student's] should ultimately conform to" (308). Newkirk's main concern with an ideal text is that if a teacher has an ideal in mind, then they are likely to dominate the writing conference and not afford the student the opportunity to brainstorm, reflect and learn from their own writing and thoughts because the teacher will only be gratified if/when the student conforms to the ideal. If this is the case, then it seems obvious that there is no collaborative learning; the teacher will most likely always be disappointed, the student will ultimately need the teacher write the paper for them, and learning/research are certainly kicked to the way side.
Do all teachers have an ideal text in mind when it comes to conferencing? I should think so, and I wouldn't necessarily cast the ideal in such a negative light as Newkirk does. In tweaking the definition a bit, I would say that an ideal text largely consists of the experience and knowledge of the teacher. In other words, our understanding of composition, grammar, structure, organization, style, tone, etc. contribute to the creation of an ideal text. These things are not bad in of themselves so long as we teachers are flexible with them and use them sparingly as one of many reference points during a writing conference.
If our agenda is to impose our ideal text onto the writer, then Newkirk's concerns are correct. We will be bad teachers, the students will hate writing and be less apt to participate in dialogue, thus collaborative learning has been terminated. But if we are willing to use an ideal text in the likeness of an organ donor--that is, occasionally rip something (e.g. thesis, transition, etc.) out of our ideal body and offer it up as one of many potential examples, then an ideal could benefit the student's thoughts and writing. Newkirk's concern is simple: an ideal text leads to bad writing conferences, and bad wring conferences are detrimental to collaborative leaning. I would argue, however, that it is not the ideal which is bad, but instead, what we choose to do with it. On that point, wearing a "What Would Plato Do" bracelet might be a bad idea.