Facebook statuses take the form of your name (linked to your profile) followed by whatever you type in the box. Many people take advantage of this to make their name the subject of a sentence:
Russell doesn’t update his blog much.
But this is by no means universal. Many an update on my home page look like
Russell updating your status is boring
And many other sorts of formats. But what about the comments you can leave in response to others’ status updates? Those too begin with a linked, correctly capitalized name, but I have yet to see (or at least remember) a comment that used that name as the subject of a sentence. They all look like
Russell that’s great, Bill!
Russell thinks that’s great!
Russell wonders why.
I thought it might be because the main status field tells you your name will appear in the beginning of your feed, while the comment field doesn’t. But that’s not true. It doesn’t seem like the different prompts (what’s on your mind? vs write a comment) would necessarily do it. Maybe it’s about topicality: the status is about the status-holder/typer, but the comment isn’t necessarily about the commenter.
Or Maybe it’s more historical? Earlier, all status updates started with “[name] is”, but even with the demise of that restriction people still like to exploit the fact that their names appear right before their custom text. I don’t know when comments started being implemented, but perhaps they came in after any facebook-enforced subjecthood requirements, so the custom never caught on.
Or maybe it’s something more genre-like: the status is an broadcast announcement, so it makes sense for it to be a sentence about you, while the comment (while also potentially readable by everyone) is more personal and so a more flexible information structure and syntax is needed?