The road that my friend and young daughter were recently killed on was closed for 16 hours and I've got no doubt that people were inconvenienced and put out by the closure and being held up in it, but I can guarantee if you are ever in the unfortunate position that it's your friend or relative involved in that accident you'll be forever grateful to the emergency services for the time they spent while it was closed to ensure you have answers and potentially justice whilst doing the following:
Passersby stopping to help at the crash and trying to provide first aid
Time for emergency services to arrive
Unfortunately my friends young child was killed on impact but they tried to stabilise my friend whilst the fire service worked to free her from the vehicle and then a suitable place found for the air ambulance to land and for the ambulance to transfer her to the air ambulance to get her to the trauma centre in the next city.
The fire service then had to make safe the scene whilst police investigators arrived to begin their meticulous assessment and preservation of the accident and the scene.
Then when the police were done the undertaker then had to be called to remove my friends child and the police then continued with further photography and investigation and finally recovery of the vehicle and clear up of the scene which isn't always simple or easy.
From working in this field I can tell you also that first priority is preservation of life and then scene. Resources will be found as soon as possible to free traffic by turning them around but this isn't easy, a diversion needs to be set up and traffic turned safely in a way there's no conflict with other traffic. If someone calls 101 or 999 and reports they have a baby or a medical need or something else then the police or other services will do a welfare check and provide aid.
Before you make posts like this, stop and think for a moment and put yourselves in the shoes of the families, friends, victims and emergency services shoes and have some compassion