If you start burning 5,000+ calories per day eating enough can feel like a chore. That's outside the realm of possible for a 40+ hour per week office drone, but it does apply to some people.
https://www.nytimes.com/2018/02/23/sports/olympics/cross-cou...
Burning 15kcal per minute is a stretch for most people, and with family life and economic constraints, I doubt most people can spare more than 30 to 45 min per day for HIIT exercise. My point is its only realistic to budget burning 400 to 600 kcal due to exercise.
It's far easier to eat more than what any normal person can burn even with excercise, so without a naturally high metabolism, a proper, restricted diet is a necessity.