@"Lauren L" honestly I don't know why, though I assume it's because they feel you're making them read something unnecessary. What I do know for sure is that it's happened, especially at Harvard.
my concern about age is that while many people start law school in their 30s, I haven't managed to find more than 2 people who go to top schools like Harvard or Yale in their 30s. Do top schools discriminate more in terms of age?