If you perform a scheduled repairs or emergency repairs yourself, You get the parts from several different wholesalers and lose a lot of time to find the best options, or You lose your money if the price search is not performed.
The advantage is that you can request any item - from bearings up to electronic circuit board at a single source fast and for a low price.
You don’t have to send hundreds of different quotes or edit answers by this you are saving a lot of time and money.