i think you only need to cook them if they are hard. if they are very ripe and you are able to puree them without cooking then you can do that. if you do cook them iu just peeled fruit and cut into chunks and either boiled or steamed until you can cut in half with a fork, then puree in blender... HTH
someone else might have a reason for the cooking, but i was under the impression that soft fruits / very ripe could just be mashed up (ie banana, papaya, etc) so woudl apply that to any fruit that was tender to the touch