Careful with the spoilers. I haven't watched the IndyCar race from this weekend yet (it's on the DVR).
IndyCars have way more downforce than F1 cars, but they get much of that from the undertray, rather than from the wings. This means they can still pass with only a little assistance. Downforce is fine as long as it doesn't get interrupted by following another car.
There are so many ways to solve this problem (crap, reintroducing movable aero parts would fix it in 10 minutes), but in F1 the teams have to approve everything, and none of them want a level playing field, so nothing meaningful is going to happen. We'll just go from one dominant team to the next.