No it is not necessary to rinse dishes before putting them in the dishwasher.
However if your dishes do have food particles on them and especially if the food particles are large food particles those food particles should be cleaned off or scraped off the dishes.
If the food particle are left on the dishes and then you put the dishes into the dishwasher then the food particles can eventually clog the dishwasher.
So it's best to get the large food particles off the dishes and then place the dishes into the dishwasher.
However if the dishes have sauce or other things that are not hard then the dishes can go directly into the dishwasher without an issue.
The dishwasher should do most of the cleaning of the dishes.
Also if you have pots or pans that have grease or cooking oil in them make sure to wipe the cooking oil or grease out of the pans or pots because the grease and cooking oil could clog the dishwasher and your drain lines as well.