I couldn't think of any use case for measure (continous).
Group is for discrete values and range is for continous values.
Numeric value is automatically assigned to "Measure" but sometimes user needs to handle it as "dimension".
It is easy to move that field to dimension manually, but Tableau cannot judge it automatically of course.
As long as it's dimension, "grouping needs" is possible/natural
"Grouping measure" means change the "continuous measure to dimension" , then grouping.