When I make rhubarb I generally just bake it for 15-20 mins (chopped up and sugar added first) and serve as stewed fruit with ice cream or yogurt.
When I make an apple crumble, I do not precook the apple. The apples cook in the 30-40 minutes it takes for the topping to cook.
So why are rhubarb crumble recipes telling me to precook the rhubarb? Surely it, like the apple filling, will cook in the time it takes for the topping to cook?