Everybody has developed abs, as long as their able-bodied. They keep you upright all day. You just can't see them. The only people who ever need to target their abs are competitive bodybuilders.
Put another way, there are benefits to exercise beyond calories burned.
I personally (Richard Boegli) lost 40 kg in 40 weeks (90lb in 9 months) WITHOUT exercise. [90lb in 9 months (no exercise)].
I chose to do it WITHOUT exercise, as my theory was that I would keep it off longer, if it wasn’t dependent on exercise. Every other time I lost weight in my life, it was a combination of diet and exercise. When the exercised stop, the weight would creep back up, as I was still eating too much.