I don't agree with this assessment. If a college requires an essay, it is because it has holistic admissions and wants to get to know its applicants as more than a list of grades and standardized test scores. The essay is typically the most powerful tool you have for conveying who you are and what you care about. If you've chosen the right focus for your essay—one that reveal something meaningful about you—you're going to need far more than 250 words to provide the type of detail and self-reflection that makes an essay effective.
Avoid slipping into clichés or generalities. Take this opportunity to really examine an experience that taught you something you didn't previously know about yourself, got you out of your comfort zone, or forced you to grow. Sometimes it's better to write about something that was hard for you because you learned something than it is to write about something that was easy for you because you think it sounds admirable. As with all essay questions, the most important thing is to tell a great story: how you discovered this activity, what drew you to it, and what it's shown you about yourself.