As someone who has extensive experience with both, I humbly submit that this assessment of the comparative time requirements of editing Wikipedia and blogging is not a universal truth. While blogging, when I was doing it at my peak, certainly did take a measurable number of hours (assuming the following tasks: writing and researching your posts and putting links into them, reading other blogs you follow and following links from them, and adding comments to posts elsewhere that may or may not link back to your own posts (and this is assuming you don't have a comments section of your own to manage)) from my day, it's been about five years since my last blog post because, among other things, Wikipedia was beginning to claim more of my interest. Today I honestly feel I spend more time editing/taking pictures/processing and uploading pictures/doing administrative tasks than I ever spent on my (anonymous, and it's staying that way for now) blog.

For the stereotypical momblogger that we seem to be talking about here, I think it would take less time to blog (And I can also speak from experience as the stay-at-home parent for this time period, too) than edit.