That's different than using the exit interview as the opportunity to let out all your frustrations and to "get back" at the company.
For example, say, "I'm tired of filling out TPS reports and I felt underpaid." No can argue with your emotions, and it's not like your aversion to unnecessary paperwork or need for a decent salary will get out and kill your career. If enough employees leave for precisely these reasons, that may eventually cause change.
What i'm saying is that it usually doesn't. Usually the feedback that you give is already known. The good companies would have changed it before the company left. Especially if it's a huge known problem.
If you're not going to answer their questions about why you're leaving you might as well save everybody's time and skip the exit interview.
You will make a difference. Believe in yourself .
It's quite possible to simultaneously be honest about a toxic work environment and to do so as a professional.
That's a good angle to take. And the choice of words and tone here is key -- it's not a rant, and it doesn't finger-point. It puts the emphasis on you, not them -- and it basically says "look, I'm disappointed and I'm suffering", thereby engendering empathy.
But if in fact they listen carefully, it also expresses criticism which can be quite damning. I like language that works like that.