Using an oven while the dishwasher is running is generally safe and should not cause any significant issues. The two appliances are separate and designed to function independently in a household setting. There are no inherent safety concerns in using both appliances simultaneously.
Your parents' concerns might stem from other reasons unrelated to safety. Here are a few possibilities:
Electrical load: Running multiple high-powered appliances simultaneously might put a strain on the electrical system, especially if the kitchen's electrical circuit is not designed to handle heavy loads. However, modern electrical systems are typically equipped to handle the demands of various appliances running concurrently.
Utility costs: Running multiple appliances at the same time might increase electricity and water consumption, leading to slightly higher utility bills. If your parents are trying to conserve energy or water, they might prefer that you stagger the use of these appliances.
Noise: Both the dishwasher and oven can generate some noise during operation. If the kitchen is located near common living spaces, your parents might prefer to avoid running both appliances at once to maintain a quieter environment.
Household rules: Sometimes, parents might enforce certain rules or guidelines in the household without specific reasons. It might be their preference to avoid using multiple appliances at the same time, regardless of any technical concerns.
To address your curiosity, it's best to have an open and honest conversation with your parents. Ask them directly why they prefer you not to use the oven while the dishwasher is running. Understanding their perspective will help you gain clarity on the issue and might also lead to finding a compromise if necessary.