I've never used a rake in association with drying hay - only raking after it is dry to form windrows for the baler to pick up. You are absolutely correct that if the hay gets wet in a windrow, it's a mess anyway (although I know we've turned it over with the rake to get the bottom to dry, it's still far from optimal). However, without raking, I'd have to make 2, 3, or 4 times as many "laps" around a field to get all the hay picked up, at a much slower speed than what I can rake, and I'm sure my baler pickups would still leave some hay behind.
To clarify, I cut with a disc mower, so I don't know if a practice of note raking is associated with a different type of cutting apparatus or not.
Good luck and take care.