I've assumed for a while that's the real reason they have it any more. Years ago it made sense that you checked in when you got to the airport so they knew you

I've assumed for a while that's the real reason they have it any more. Years ago it made sense that you checked in when you got to the airport so they knew you were physically there and they wouldn't give away your seat. But now, checking in from home up to 72 hours in advance sometimes completely fails for that purpose.