I don't think the racing was much better before hybrids. You only had two teams competing for wins just like now (in the ILMC). Except they had diesel engines. In the ALMS it was a rule tweak and some more power for lmp2's that kept them with the R10's. Then when Audi left ALMS, it was Acura vs Porsche for a little bit until that was gone. Then you had the occasional p1 battle with Dyson vs the Acura with the latter cleaning up most the time. Now you got the same Cadillac winning, even if it starts at the rear of the prototypes
The more things change, the more they stay the same!