A lens can be very usable hand held for a little while. That same lens may not be as usable hand held when aimed continuously at potential subjects for several hours.
I shoot high school football with my heaviest lens on a monopod. From the sideline most of the action begins between the hash marks and is in the same general direction from my position over the course of each play.
I take that lens off the monopod for the halftime show, where potential subjects are closer to and even on the sideline and they are spread all over the field at a much wider range of angles to my position.
After halftime, I then put the lens back on the monopod for the second half, when most plays are all shot with the camera pointed in roughly the same direction.
The halftime show lasts about eight minutes for each band. I'm there mostly to shoot one of the two. The football game lasts 48 minutes on the game clock, plus the time when the clock is not running until the next play starts. Each half usually lasts around an hour to an hour and twenty minutes or so. A lens that is not too heavy to hand hold for eight minutes can be too heavy to hand hold more or less continuously for two and one half hours.