what is the use of certificate without private key in efs

Now with a lot of files having encrypted with the EFS, I got a backup of my certificates in order to prevent any data loss in the future...
But while doing so I got an option whether to export private keys as well...Well you will need the private keys to decrypt the header...isn't it??? Then why keep a backup of the certificate which don't know the private keys and hence don't know how to decrypt the header to get the bulk symmetric key????

So what's the utility of this type of backup??? Some tutorials say that you need them when you apply the backup on a different system???