You create this writing. Yes, you do. I write the words, their coherencies dancing to my inner rhythms, but you create the meaning that the words impart. You, the reader, control my writing. Okay, that is going a little far, but I do write for your reading. When you completely miss the point of what I wrote I think it's me, not you. I wasn't clear enough; it's not that you have problems with comprehension, though in my darker moments I will admit I've thought this.
There are different groups of readers too. Who comprehend differently from each other. Offering your writing to different groups can be an interesting experience. But I won't get into that. Oh, and whoever leaves the first comment often defines how that piece will be interpreted and responded to. I often make it a point not to read the other comments until I've commented. I want a pure connection with the writing that doesn't need to line up with the 'group-think' because it's sure of itself. I personally like independently thought-out comments. On the other hand, when discussions get going, that's great too.
The comments often enable the next piece of writing. We are audiences, then, who shape each other's writing. It's reader-response carried to a newly imagined level, this critical approach to literature, but greatly speeded up in the blogosphere. The process of reception and meaning-making that enables the writing to live beyond the page it is written on.