A home sub-directory is owned by a local account. The requirements for a SFTP chroot directory is that it can not be writeable by any user or group other than the ‘root’ account. But the user directories in /home are always writeable by the owners. For example /home/ben is going to have read, write, execute permissions for the user and group ‘ben’, so it is not usable by SFTP chroot. If you want to set it up for SFTP chroot you need to remove the +w write permission of /home/ben for the user and group ‘ben’. But that means the local user ‘ben’ can not write or save any changes to its home directory making it useless.
You’re better off creating a separate SFTP container directory such as /var/sftp/ben/ with root only write access and using that for SFTP hosting.