The weight of the material is supported by your shoulders, and not your hips, which is far more comfortable in general
In addition to having more room for pockets, overalls can carry heavier things without falling down, nor need for a belt
Since the weight of the material is carried at the shoulders, bending down at the waist is easier and less restricted. The waistband no longer needs to be tight, since it no longer serves a functional purpose
I feel the problem with pants isn’t weight related, since that’s honestly neglectable with clothing, but with how they put constricting pressure on your waist.
I loved it when I wore overalls at my old job, it felt like I was being naked, while also having soooo many pockets