Well, I don't know for sure but I'd guess to prevent a very well funded team from sending out three boats with current sticks to track the wind shifts and current for a few weeks beforehand. They do it in the America's Cup and some other high profile regattas. I would find it discouraging if I arrived and found out that you had spent three weeks studying the wind and current patterns and had a secret trove of data. Discouragement leads to not attending next time which leads to smaller regattas which leads to cancellations.
Have a Hobie day!