By the same token, when something is pushed to all those users and makes relatively little impact, that's a huge opportunity cost for FB. Each time they try something new, it will alienate some users, whether they just visit FB less or stop using altogether or whatever. They would prefer that new products/services make up for that one-time user cost with compensating increased "stickiness" for other users over time, or some similar benefit. They can't annoy their userbase without limit. Or maybe that's just wishful thinking on my part...