You can technically still do this with 3.5" disks, it's just a invitation for horrible mechanical problems when (not if) the disk touches something it shouldn't

You can technically still do this with 3.5" disks, it's just a invitation for horrible mechanical problems when (not if) the disk touches something it shouldn't or unseats from the drive motor. Also you need to manually push various latches and levers that the sleeve would have run into.