That's what I'm trying to figure out too. For that matter, why couldn't I just take the messenger.com site and wrap it in a Chrome app myself (which is what this looks like anyway)? That way at least, I can be reasonably sure I'm not leaking my FB credentials to a third party. I know the average user won't know how to do that, but then the average user would just launch messenger.com in their browser anyway.

I guess what I'm trying to say is, who is this for?