The Lone Ranger writing teacher is a common problem. An early elementary teacher has their work cut out for them if the writers they receive at the beginning of the year think that writing is filling in the blank ("I like to ____.") or writing letters to represent missing sounds on a worksheet. That teacher can make huge gains with those writers but can surely imagine how much further along they would be if they had arrived with a different skill set. Those young writers might then head to another grade where writing is solely directed by teacher prompts and topics. The writers will grow in that place, but they might lose a bit of their motivation or personal connection to the process. In the situation I've described, as writers progress from one writing environment to the next, I believe the disconnect between foundational practice can impede student progress.
I am the last person to say that all teachers must be on the same page. In fact, that's one of my least favorite teachery thoughts of all time. I do believe in the importance of being on the same pedagogical page though. I agree with Calkins that vertical alignment and agreement about best teaching practices is vital. The CCSS is raising the bar for our writers, and I believe it's totally within their reach. They just need their writing teachers to step up their game and give them consistent excellent writing instruction from one grade to the next. Anything less is simply impractical.