They are merely a way to understand what the rest of the team is working on and to make sure you have the resources you need to do your job without having to interrupt you later or are you having to interrupt somebody else later it takes 15 minutes and it often saves hours of wheel spinning.
It serves no purpose because if you are blocked today waiting till a morning meeting is a bad approach because the meeting than expands to discussing an issue that belongs at another meeting. Plus the time wasted adds up.
Asking for help today is something seniors do.
Standup meetings treat developers like children and encourage bad habits.