Of all the big carriers, I've never heard of there being a problem with a driver not wanting to risk driving in unsafe conditions, even if another driver made it OK over the same roads. The fact that another driver made it safely on the same roads, in a different truck at a different time with different weights and different tires and different all kinds of things is irrelevant. If a dispatcher tells a driver to keep going after the driver says it is unsafe, then the dispatcher and the carrier immediately take on a serious chunk of liability if anything were to happen, whether they realize it or not.
Every time I've talked with dispatch and mentioned bad driving conditions, the response I get is generally along the lines of, "If you feel it is unsafe to continue, do not hesitate to pull over until conditions improve. If you don't think you can make it, don't try."
I've driven in bad weather and pulled off to get fuel, and come across other drivers from my carrier who were parked there waiting for better conditions. Happened just a couple of weeks ago. Even though I continued, those drivers felt it wasn't safe, for them, to continue, and the carrier didn't have a problem with that.
Just because one driver is comfortable driving in certain conditions doesn't mean another driver will be, or even should be, comfortable in the same conditions. No one should ever feel pressured to drive in conditions in which they are not comfortable.