I understand your concern.
With the caja packages installed, caja would have the capability to see and edit extended attributes. However without user_xattr as a mount option, the underlying ext4 file system will not feed the attributes to caja. —so it won’t work. My understanding is that user_xattr is the default in Debian and some other distros, but is not the default in Ubuntu.
I don’t know how your disk and filesystem is partitioned–you would only need to enable the user_xattr mount option on the partition which contains the data you want extended attributes on. Many people put at least /home, /tmp, and sometimes /usr or /usr/local on separate partitions from root for various reasons. If you are all on one partition, you would, indeed, have to change the mount on root; if /home is a separate partition, you need only enable it on /home–you should be putting all of your user data in /home/ somewhere.