.MASSHOLE.I don't know if the current generation has changed, but the mid late 2000 versions were pretty light which meant they weren't always great in the snow. Obviously snow tires can help but even then, we used to put sandbags in the trunk to get more weight over the rear tires.
It's not a weight issue, I think it's a differential issue. All the diffs are open, so torque will always bias where there's the least amount of traction, such as the rear end in your case. The limited slip in subaru's center diff is part of what makes them so good in the snow. When you put weight in the back, the car will then more evenly bias torque so you get more traction. Semantics, I know, but I'm a dork about this shit.
Idk if new models remedied this. Some brands bias braking, some use clutches, etc to redistribute torque to the wheels with traction. Idk honda does now-a-days. My mom's 2010 crv is pretty shit in deep/rutted snow, but for the most part does well enough in most snowy conditions.