Can't invite friends on anything but projects?

When you post a new project there’s a nice little box at the bottom – ”Invite friends by email” – where you can put in email addresses of people you’d like to “come on over” and look at your latest creation.
I’ve just finished writing a little bloglet, and I looked for the “Invite friends by email” box and it wasn’t there. I checked “Forum topic” and it’s not there either. I didn’t check reviews, but I suspect it isn’t there.

I’m just wondering why?
I would have liked to invite a couple of people to my bloglet, and I think some reviewers might like to invite friends too. Not sure myself about Forum Topics, but why not?

Anyway – I think it would be a good idea if you had the same “Invite friends by email” box on all postings, be they project, blog, review, or forum topic.

-- "Do not speak – unless it improves on silence."