Feeds are monitored 24/7 and feed providers do know when the feed goes down (we have a monitoring system that alerts them). Many feeds are provided by volunteers and sometimes, for many different reasons, feeds can't be up 24/7.
Posting here in the forums every time a feed goes down doesn't help - when feeds are down for a while we are already looking into it. That doesn't mean the feed will return - especially if the circumstances are beyond our control.