I think I've found out why: because, a lot of the time, you're simply not allowed to talk about what you're doing; even if it's not TOP SECRET, there are other people involved who haven't given you permission to associate their name with yours, and to do so without permission would be tacky at best and grounds for a lawsuit at worst.
So, I could write an entry about my Friday that sounded like this:
Mike was waiting for a call from , who isn't doing business with us (yet?), but we thought might be a cool source of ideas for our new product, , because he has so much experience in the area. I mean, he *IS* the of !
So the phone rings, but it turns out it's ! From ! He's all, "Can you and Wil have a with me today at three?" and Mike's all, "Sure!" (because, hey, all we ever do is hang out and drink coffee, so we're really always looking for any distraction).
Mike calls me to wake me up (it's well before noon, doncha know), and tells me about the day ahead. Mike's all, "I hope doesn't call when we're talking to ! That'd be too funny! I'd be all, 'Oh, could you hold, I have Blur Blur on the...'"
[Ok, you get the idea. I'll spare you.]