Productivity reports are not just intended purely for exhibitionism. Part of it is to keep my own writing on fiction transparent, so that if I ever make any gains, everyone can see what I did to get there and how long it took. For example, short stories might be submitted to ten or twenty different places (or more) before they get picked up. It can help demystify the process to see that there isn't some magic that causes fully formed stories to simply appear published in a forum. It takes a lot of work and a lot of rejection, and I'm going to give you the blow by blow so that you can see. Mostly it takes work, and so I will keep a log of hours I spend on revision and word counts I accrue for first and second drafts so that if I do ever get something picked up, everyone can see how much effort it took to get to that point.
The other part of it is the same sort of reason that someone who wants to lose weight posts their weigh ins or pictures of their meals. They don't really think you care if they're having a salad for lunch, and if you do, you probably need to get psychiatric help. I'm doing this to keep me honest. It's to keep me working. It's so that when I'm tired and I don't want to, and Season 8 of Monk is looking oh-so delicious that I remember I'm going to have to post my productivity for the world to see, and the thought of millions of readers (or in my case twenty) looking down their nose and saying "He thinks THAT is a good effort?" will spur me forth.
If anyone else wants to take advantage of that benefit I welcome you to post here and we can all act as cyber taskmasters and cheerleaders to each other. Your friends and family on Facebook probably think you're nuts, but here we all have the same ridiculous obsession. Post your word counts, hours spent working, resulting page counts, submissions made--the only requirement is that it has to be concrete and measurable. None of this "I wrote a lot this week." The other guideline is that your fellow posters (or me) will be most able to cheer you on (or arch our eyebrow in dubious Spock-style) if we know what sorts of goals you want to reach.