Heard the one about the dozer and excavator on a slippery slope?

I came across this You Tube clip recently and thought it might prompt a good debate amongst our readers.

In this video a Cat D6R dozer and a Kobelco SK170 hydraulic excavator are attempting to climb a steep hill after a night of heavy rain. The dozer heads off first and really struggles to get traction. In fairness there does not appear to be much meat on the tracks which isn’t really helping the effort, but I had to keep thinking, why didn’t the excavator go first and pull the “slop” off the top first to give better traction for the following dozer.