Let's make an example.
There are 10 highly desirable rooms available and 100 members want to book one full week.
Old system:
Day one
10 people get it.
Day two.
On average, 1 person who got day one will get day 2 too, the other 9 won't get it and 9 new people will get day 2 only
Day three
The person who got days 1 and 2 has only 10% change of getting day 3 too. On average only one of the people who got day 2 will get day 3 too. One who got day one will get day three but has a night missing in the middle. A few people will now have just day 3.
Day 4
The chances for someone getting all 4 days are 0.1%. More new people get just one night. Maybe one got days 3 and 4. More and more have two or three not consecutive nights
Day 5
Situation getting worst. The chances that someone has 5 nights are 0,01%
Everyone is desperate as they get only a night here and there. They probably log in the DISboards to blame walkers anyway.
Day 6.
Chances of getting all 6 nights are now 0,001%
People start selling DVC.
Day 7
Chances of someone getting all 7 nights are 0,0001%. Which can be easily rounded to zero.
Current system.
Day one.
10 people have a reservation for day 1 and for the remaining 7 days. Some or even all of them may have walked the reservation.
Day 2 to 7. No room is available because they are all already booked.
Results.
Old system: no one got what they wanted. 100% unhappy people.
New system: 10 people got what they wanted, which is the actual maximum possible, since there are 10 rooms. No split stay. 90 unhappy people.
I understand that people may feel unfair if one or more of the 10 people walked the reservation, shutting out others. But yet, with the old system no one would have gotten it. I cannot see how this would be better.