The answer Apple has given is correct.. You can do it but you should NOT do it.
The reason you have a large disk with a small laptop is Time Machine will do incremental backups until it fills the drive.. so it uses a lot of space.. eventually when it runs out of space it will delete the old backups.
Your question is not uncommon ..
Store files on the TC.
This is asked several times a day.. obviously people are struggling with their latest SSD being too small.
The TC is not suitable for network file server.. but many people having no choice press it into service as such.
It cannot be partitioned. It was and is and ever shall be a backup device for Time Machine.
1. No backup.. no way Time Machine can backup a network drive. No place to backup to.. So all your files will be at risk. And you will need to buy a third party like CCC to do backup.
2. The TC cannot be partitioned and mixing TM backups and data is not great.
3. The drive is slow to spin up and quick to spin down.. there is no controls.
4. iPhoto in particular can easily corrupt its entire library with wireless networking causing a disconnection to one photo. Even if you do this;;; do not move your photo library... you have been warned!!
5. iTunes will constantly lose connection to the library. The disk is too slow to respond.. itunes on the computer will constantly spit out errors. Even in the midst of streaming the TC can spin down the disk due to caching.
6. Do not use any live files on the TC no matter what else you do.. if you edit files in whatever program the file must be on the local hard disk.
7. The only suitable location for most libraries is a computer. You can plug in an external hard disk.
Read pondini for some work arounds.
Q3 here. http://pondini.org/TM/Time_Capsule.html