No they're not beating to windward. If you do some searches on here about sailing with spinnakers, you'll find all the discussion(s) that went on about the fastest way downwind. Essentially, with kite up you are travelling fast enough to create an APPARENT wind that means you need to sheet in your main. There are several other reasons why this helps the boat and is explained at length (with various author's views) in those threads.

Have fun with your new spin!