Because software is often developed in stages. Do you remember the old paper FP kiosks? When it was initially rolled out they accepted just about anything "Disney" for a FP: active ticket, expired ticket, room key with no ticket, etc. Then, sometime later, they added the software to verify that the ticket was activated in the park. Same thing with FP+. The kiosks accepted MBs without active tickets and now (as I understand) the kiosks will no longer allow you to book SDFPs without having an activated ticket. What I have read is that they tried to verify MB/ticket activation when they first implemented FP+ the but the system crashed. So they rolled back that capability until they could implement it successfully.
Exactly which scammers will not go away with a blue mickey?