I think it depends on the type of writing in question. Writing may be one of the only things that so many people tend to just lump all into one thing, when writing is like speaking (we speak for all different reasons and in all kinds of different situations). So much writing is pretty much nothing but craft/skill. A "standard web article" is most often a streamed down type of thing in most ways. More specialized articles in different fields are "more advanced" version of the "craft/skill" type of writing.
I don't write fiction, and I'd think a certain amount of creativity has to be involved a good part of the time. Then again, most of us heard how people will write some fiction based more on formula than genuine creativity.
With many things I've written online over the years (and before I removed any number of things as part of all the changes over the Internet since Panda), I wrote from previous research but in a more casual way (simply because "casual" was OK enough at the time and for my purposes).
My own non-fiction stuff that would be considered "creative non-fiction" doesn't come from a shred of creativity. I seriously lack creativity (or at least I have little patience for it in the "scheme of" whatever else I want to write, do, in life. Still, even though I feel like I outgrew any creative urges I had when I was younger, they were fairly limited right from the start.
If I think of a book like Harry Potter I can't even imagine coming up with that kind of stuff. That may be because even when I read fiction as a kid I preferred "realistic" fiction, but also, I started preferring non-fiction pretty young. (Again.... lack of creative-leanings, I think). I know all kinds of people who say they can't write or hate writing but who are pretty darned creative (even "wild") with use of words in conversation than I am.
I'm a stickler for accuracy of words and subtle ways different words can say the same thing better, and I'm an arranger of words. In some writing I'll call upon some old and "filed away" emotional experiences that have become nothing but words at this point. As an arranger of words that's about as "non-non-creative" as I can most often get.
Of course, I'm thinking of "creativity" as imagining up something completely new, rather than, say, "get life onto paper" (or represent real life in some form of art, although that's seldom my motivation either).
So, after all that, I think the answer to this question is, "It depends"