I have no problem with other boats going downwind while I'm going downwind, usually, because we are going nearly the same speed and we can usually see each other. It's when I'm running downwind and some guy is coming upwind, in my fleet or any other fleet.

Or maybe there was no problem when he rounded, but then he tacks, I never see him. Maybe he never saw me coming, or he thinks it won't be close, then a puff comes along and I've got to bear off deep...all of a sudden, it's a problem and I'm busy trying to keep it upright, not looking out below, in the blind spot the spinnaker causes.