Downwind the spin throws up a giant blind spot and it's just a matter of time before someone gets hurt. There are a couple of "too close for comfort" stories going around with reliable witnesses in support.
Anyone for changing the right of way rules? I have it on good authority it can be done in the SI.
All spinnakers have the right of way all the time! Yeah!
(actually, spinnaker foots got a lot higher and are easier to see under than they were in the early 2000's.)