- not possible to write an ISO/IMG file to a SD-Card, eg. for my Raspberry. Raspberry Pi is a learning Computer. Can't prepare the system with an iPad.
- not possible to do local backups of all preferences and data (the stuff in ~/Library on a Mac) - iCloud don't store everything = iCloud isn't a proper Backup solution
- Example 1: my saved offline Pages in Pocket App won't be backed up. It need to be loaded again - if they still exists. I can lost important pages
- Example 2: offline Maps won't be backup to iCloud, need to remember (better not 1 minute before a trip with only mobile data) and download it again
- Example 3: even if it's a encrypted backup, some App passwords won't be backuped - need to write it down somewhere
- there are a lot more examples that won't be "backuped". The word "backup" is joke if it comes it iCloud backup. iCloud Backup isn't a real backup in this form - never ever.
- not possible to do local backups to external USB drive or network share of all my files
- long running downloads in the background are impossible. I need to be a slave of my iPad and let the App always be in the foreground or don't forget it after 10 minutes, when iOS kills the App
- not possible to have a Terminal for basic Unix commands
- not possible to attach it to an external monitor to have a bigger display with external Keyboard and Trackpad for ergonomically work
- not possible to do even basic web development, because display is too small. For web development it's also needed to check against other Browsers (Firefox, Chrome), but they all need to use Safari Render Engine in iOS.
- it's even not possible to look into the mail header if a suspicious mail arrives
- it's even not possible to export my Bookmarks from Safari and import into Chrome Browser if I decide to switch to this Browser...
This list can be filled 10x.
iPhone and iPad are really great additional devices, really like it. But they are far away as a one and only device, if the user want to go up one step from very light IT technology to light IT technology. Both devices are also ok, if a user never cares if he lost personal informations.