I read a book last night that had no more than 25% of its pages as dialogue, and even then the dialogue was a brief sentence followed by several sentences of description. One chapter I found had almost no dialogue in it at all. Now, mind you, the main character did a lot of talking and there were A LOT of other people in the book, but they rarely spoke for themselves. Instead most dialogue was filtered through the lens of the main character.
For example: Most of the primary grade teachers were planning the usual art projects along with having the kids bring valentines to give to everyone in the class. Alicia Despain, who taught fifth grade, plus environmental science to anyone who would let her, argued that it was a terrible waste of paper to throw away all those valentines every year, but most of the primary-grade teachers defended the practice. "The kids like it," said one of our first grade teachers, and someone else added that it really helped the students with practicing their letters and their handwriting coordination.
There are times when it is safe to let the main character describe everything from his/her point of view (POV), but it tends to make the rest of the characters seem like lifeless talking heads. We are never able to hear what they have to say for themselves. You may want to create a dominant POV, but it is a fine line between dominant (primary) and domineering (tyrannical).
Dialogue is essential to break up the flow of your writing and to provide some variation in what you are saying. No one likes to pick up a book and find massive blocks of text and little white space-- especially when it's a child/teen picking up that book. White space is visually appealing and less intimidating than BIG blocks of description, no matter how beautifully or cleverly writtent that description might be.
Finding a balance between dialogue and description is one that every author must create for themselves. I know great authors who struggle with description and end up adding it in through the final editing process to break up their scenes. Authors like myself are exactly the opposite. When I'm editing, I have to add in description to "fluff" out my scenes. The balance line between the two is different for every author and, I believe, for every story.
Now for some homework. If you want a description-heavy book, try anything by James Michener. He'll show what thorough description is, plus he may help you fall asleep at night! ;o) If you want a book with ALL dialogue, pick up "This is What I did" by Ann Dee Ellis. Her book is a remarkable example of a book with NO prose. Everything is a thought or statement by the main character or his friends/family.
Find your own balance. If you are not so good with description, then write a scene that is entirely dialogue with an occasional "he said sourly" or "she said tearfully" so you can keep track of who is speaking. If you are great with dialogue but are weak in the description department, then try writing a scene where two characters are interacting with each other but no one says anything involving " " " ".
Experiment. You may find you're the next James Michener or you may find your characters can pack a punch in what they say. You never know until you try.