The evidence needs to be judged on fitness for purpose - that is, does it convincingly answer the question asked?

If you're a nihilist, then feel free to start with the answer, “I don't have a purpose,” or “Life is meaningless,” and take it from there.

Another purpose is to improve performance based on partition elimination when the DB2 query optimizer determines that only a subset of the partitions need to be examined to answer as particular query.