This is exactly what is happening now. It used to be they just gradually started letting people in a little early pre-9am and people calmly walked to the ride they wanted to do first. Thanks to people getting scanned/going through turnstiles you never had a huge crowd at once, it was staggered nicely.
Now everyone gains entry in advance, but are all stopped by ropes at the hat to watch the Opening Show, then once it is over the ropes are dropped and it becomes a free for all to get to TSMM, if you are not there within the first 100 or so people, your wait time will be a half hour. If you are not within the first 200, you're looking at an hour....by 9:05am.