Others have written
There is no upside to telling the truth.
If your only consideration for saying something is whether it benefits you, then they are right - there is no upside. However if you are prepared to take some action that might help others, then saying something like the truth can be helpful. Your boss might learn, the company might learn, and that might benefit the colleagues you have left behind.
Obviously what you don't do is "rant about the reasons for leaving". In fact ranting about anything is pretty much never helpful at any time. Instead present what you have to say in a calm and dispassionate manner. Consider asking your boss whether he wants honest feedback. Also don't present your relationship with your manager as the "only reason for leaving". It isn't You are getting a pay bump, better benefits, and a signing bonus. Feel free to tell your boss that.
If you want to say something about your boss, try
I did feel that I could have been better supported by management. I didn't have an opportunity for regular meetings, and I felt there was little goal-setting here.
Don't make it personal, and absolutely don't get in an argument. If he tries to tell you reasons, or explain his approach, just say that it was something you felt, and wasn't your main reason anyway. If he tries to make it personal, just stop talking.
And if you don't feel that you would be able to maintain a calm demeanour, then don't say anything.