I still don't really see the use, but maybe there are large swaths of people who stay home until they can leave at the very last minute.

I'm almost certainly going to be waiting at the airport anyway by the time the delay is confirmed.

Last year Flighty literally saved me from an overnight delay because it notified me the incoming aircraft was still on the ground at the previous airport. I was able to snag the last couple seats on a later scheduled flight which actually departed. My original flight ended up getting canceled.