When our service is down for some reason, the ONLY question we get (like this one we got today) is - "Has the service been down recently? If so, no worries - it happens, just wanted to report and see if this is temporary or if it is just me."
Having a "holy shit our entire service is down" message means your users dont' have to ask "is it just me?".
That's a big difference. It has nothing to do with shifting blame, it's about keeping your users informed. Information makes people happy.