V.W.
Ignore those people. Do they have dogs? If they do, they are probably OVERweight. On any dog, you should see a difference in their abdominal area (the place where there ribs end and just in front of their hips) from the rest of them. If you can't SEE ribs, but you can feel them with your hands, then your dog is probably at the right weight.
In America, most family pets are overweight. So what people are accustomed to seeing is overweight dogs. If you think overweight is what is normal and good, then seeing an actual proper weight dog makes them look too skinny. And if you have a large breed, having them a slight bit underweight is better than a slight bit overweight. (per my vet).
Like humans, carrying around extra weight is hard on their bodies. Hips and hearts especially.