There are those who will take issue with the terminology “dream” school. But if your kid has a clear favorite school and the Net Price Calculator returns an affordable result, then ED makes sense if the student & family don’t care about seeing other results, if they were to get into that school.
Where I think ED strategies can be problematic is when one is choosing to ED to a school that is not one’s favorite because one thinks that “using” ED will get a bigger benefit at a particular school than one’s favorite school.