I have read that reduing mean pressure in distal arteries (e.g: lower limb) maintains blood flow there. How can this be true if flow=pressure/resistance, and resistance is highest in the arterioles?

You may understand that in order to reduce mean pressure (MABP), you may have to dilate your vessels. By extension, you may appreciate that vessels with a larger diameter possess less resistance. Ta-da.

Another phenomenon you might be interested in, is the windkessel effect (look it up on Wiki), it's a phenomenon describing why blood pressure doesn't fall to 0 mm Hg after systole, but drops to and remains at about 80 mm Hg until the next systole