Is it crucial for scriptwriters to find an agent?

from Beginning Writer's Answer Book, edited by Jane Friedman

It is not crucial to obtain the services of an agent; you can always try sending query letters directly to producers and ask them if you can submit your script. But you’re likely to have an easier time if you find an agent, especially if you live outside the Hollywood community and have little opportunity to make connections with the people who would be interested
in your work.