Yep- this is correct.
The only benefit is that the receiver knows the cheque can't bounce, so, say, you buy a second hand car from someone, they let you drive the car away and you give them a BD. Everyone knows they havent been ripped off. They will definitely get the money.
If you just gave them a cheque, the cheque might bounce and then they'd have big problems so they might say "well the cheque needs to clear first" but then you'd say "but then you might not give me the car".
So basically, they're used to simplify transactions so that both buyer and seller swap something with a certifiable value at the same time.
They used to be more common before things like Paypal were invented.