What is done to the dogs when spayed/neutered

I find it odd that with humans they just go in and clip off some pathways or tie a few things in a knot but with animals they feel the need to remove the entire organ, I know there are logical reasons for this however I still find it odd

Spaying is done through an incision in the abdomen, and takes from 15 minutes to an hour to perform, depending on the size of the animal, the experience of the surgeon, and other factors. Surgery on overweight animals is usually more difficult to perform because of the layers of fatty tissue. It may take longer to perform the surgery on a pregnant animal or an animal in heat because of the increased blood supply to the reproductive tract. Possible complications include bleeding after the surgery and incomplete removal of the ovaries. The pet's activities should be limited for the first week or so following surgery. Dogs should be walked on a leash and not allowed to run or roam. Pets should be protected from stressful environments (e.g., excitement, extreme temperatures). After the first week, animals can resume normal activities.

Pets can resume usual meals the day after surgery. Pet owners who are concerned about their pet's appetite or weight should talk to their veterinarian.

If your pet has external sutures or staples, they are removed by the veterinarian 10 to 14 days after surgery. If medications are prescribed, label directions should be followed carefully. Call the veterinarian if there are any problems or questions.