Why bother with the dishwasher if you're already washing the dishes? I don't do any of those manual steps and my dishes come out clean. Modern dishwashers and soap are very good at the entire process.
2) a cycle will typically be much hotter for much longer than whatever you do manually. So the dishwasher is what I trust to fully disinfect my dishes
3) a family of four cooking at home will need a full load every day so it’s a lot more efficient than manually washing and drying everything, especially when both parents work
The water probably doesn't get hot enough, unless the dishwasher has a sanitize cycle.