It is what it is. 
It’s a metric with very limited boundaries. However, it does allow you to compare apples to apples when looking at different institutions. Once you loosen up the definition, it becomes impossible to compare colleges or have a baseline measure to compare against.
It’s a measure that has value, as long as you understand it’s limitations.
Of course, some schools still take advantage of it’s strict limitations, such as only counting students that enroll in the fall, by having academically weaker students enroll in the spring…these students who are more likely to drop out are now not included in the measurement.