I watch soccer basically since I opened my eyes for the first time
and I regularly watch the NFL for 4 years now and recently also watched the rugby world cup.
I can definitely confirm that rugby is much closer to soccer than football when it comes to the energy demands.
Also to my knowledge (like in soccer) in rugby every player has to have at least some ball skills and can't just be there for his size.
In football there are probably lineman who went a whole career without ever touching the ball.
Like
@wespom9 said they are just there for their size and "wrestling" skills.
In football there are guys (linemen) that seem to just serve as a wall of flesh that pushes against another wall of huge guys.
IMO that's why all the others are so heavy aswell.
You just have to be, because if you are a defensive player who wants to get to the QB who is protected by 300-350lbs guys you just can't be only 180-200lbs yourself. No way you would make it past that big guy.
The speed positions (receivers, d-backs) in football are much closer to the other sports. For them its in the range of height minus 90.
During the last track and field world championships the experts also talked alot how young sprinters nowadays start to carry less and less muscle.
Wayde van Niekerk and Kirani James are prime examples of this.