It doesn’t have to last all day–it could be for an hour or even a month.
How would you celebrate it? Who else needs to be part of it?
It’s a symbol, a marker, a chance for conversation. It can amplify culture, give you a chance to have a conversation and allow you and the people around you to focus on something for a short while.
And it might catch on. This is the way just about every widespread holiday came to be.