Sometimes you just want to write something. Maybe you have something specific to say, maybe not. Maybe you have nothing to say at all, but just want to get something out there.
Maybe you’ve set yourself a target, and having missed a day (and being aware that you’ll doubtless miss others) you’ve decided you want to keep the average up. So that at the end of 2017 you’ll be able to look back at at least 365 posts in the year.
Maybe at the start of the year, that was about as many posts as were on your blog in its whole history. So it’s a major challenge. But maybe you keep going, even with nothing to say.