You can use your dishwasher even when your dishwasher is broken. You can put the detergent at the bottom of the dishwasher and your dishes will still get washed. The dishes will not be washed thoroughly when you do this.
Therefore, it is recommended that you wait for some minutes before putting the detergents just as the soap dispensers spill the detergent at a set time.
Even though using soap dispensers is not a necessity, they are recommended because the dishes will be cleaner and the detergent will not be wasted