Getting everyone together for 15 minutes each day to ask, "How can we coordinate our work to make sure we are all doing our best to deliver the next piece the customer wants?" is valuable. Showing the customer what you built over the last week and asking if it needs any changes is also really valuable. Occasionally taking time as a team to discuss ways you can improve? Again, very valuable.
But the value comes from the collaboration each activity enables. Just because you have a 15-minute meeting you call a standup, a demo, or a retrospective doesn't mean people are actually collaborating in a valuable way.