I was discussing this with someone last night. Batman got rid of the of the yellow disc in Pre-Flashpoint before Jason came back. Bab's didn't start walking again until New 52 and hasn't worn her original suit since she was shot to my knowledge. They also state that the Joker has been around for decades, which would be too long even for Pre-Flashpoint (15 years at most). Just doesn't fit in any of the main timelines they've had.