yep, many people collect credit card bonus points, transfer these points to their empty mileage account that never had any activities, then redeem/sell an award ticket to the "friend". In fact, there are some online specialists who buy and sell mileage, points, and award tickets. This happens mostly in premium cabin booking where the tickets are much more valuable. The airlines are not stupid.
Bad things can happen: the suspicious award ticket may be invalidated by airlines without notice, the ticket holders and/or mileage account holders may be put on the airlines' blacklist.