Crock pots are one of the best inventions in the history of the modern kitchen. Not since the drain equipped sink has one device so successfully changed the nature of the game so much. And even though most people do not give the humble crock pot very much credit, its slow cooking abilities are prized for their ability to allow you to have a good meal ready at the end of the day, with nothing more than preparatory work to do in the morning. No matter how busy you may get during the day, and even if things go later than you anticipated them going, you will still have a hot meal ready without any substantial risk of fire or burning the food.
Consider how dangerous it would be if you tried to cook a meal in the oven this way. While the first few hours would undoubtedly be productive, the last few would most likely result in either burning down your home, or absolutely ruining whatever you were trying to cook. An oven simply does not have the capacity to be as safe as a crock pot does- despite its far higher price to buy an oven, all of the power it puts out simply is not designed for the slower, more subtle cooking process that a crock pot does naturally.
You could always use a microwave, of course. In five minutes, you can get something that “sort of” resembles what you would get after half an hour in the oven, or several hours in the crock pot. But microwaves do funky things to food. Not only do they make it taste strange and require non metallic cooking vessels. Some scientific reports have even stated that microwaves cook food using an unnatural kind of radiation that causes carcinogens to form inside the food. A crock pot may be healthier, but at least it won’t put weird chemicals into your family after eating from it.