Lack of notification. So you end up with a giant folder with a single "NEW NOTIFICATION" star above it. Then you have to open it and scroll through the limited 3 x 3 view.
The hard limit on how many apps a folder can hold?
If you weren't aware: You can fit 135 apps in a folder. Folders inside of folders are also supported so there's practically no limit.
Folder in folders are not supported, except via strange glitches.
I was aware since I just made that exact point. You want an "App drawer" folder that has a hard limit of 135. Not to mention the terrible UX of folders at that scale.