Why do they care, though, if their margins are going to remain at X% anyway, because of market forces? They're just adding extra steps to the whole thing so a random passenger can benefit from my lost ticket money, rather than someone I explicitly choose.
Because if a ticket is sold privately to another rather than going unused, the airline only gets paid once. If the airline can resell the seat, they get paid for it twice.
When I buy tickets, they are nonrefundable. If I don't use the ticket, I don't get my money back (or credits). You can buy tickets that are refundable, but they cost more.
