Select to expand quoteazymuth said..
This is the best explanation I've seen.
Summary - it's complicated 
That was very good, especially from a philosophical point of view (yep, single factors do not explain multi-factorial realities) ... but still ... it does not explain why I am not flying my foil consistently 
YOU can be close to perfect.
However, the wind varies by 10 mph and 20 degrees in direction....without telling you
