Why is it required to have /var partition locally available not on iSCSI disk?

Issue

• When installing Red Hat Enterprise Linux 5.9 on Software initiated iSCSI root disk, all filesystems are automatically configured with the _netdev mount option. This causes lots of services to fail during boot, since /var isn't yet mounted read when E.g. syslog, iptables, sshd, etc.. are started.
• Removing the _netdev mount option from /etc/fstab seems to fix it, but is there any reason why this option is added?
• This is the /etc/fstab installed as part of the RHEL5.9 installation:

/dev/rootvg/rootlv      /                       ext3    defaults,_rnetdev 1 1
/dev/rootvg/varlv       /var                    ext3    defaults,_netdev 1 2
/dev/rootvg/locallv     /local                  ext3    defaults,_netdev 1 2
LABEL=/boot             /boot                   ext3    defaults,_netdev 1 2
tmpfs                   /dev/shm                tmpfs   defaults        0 0
devpts                  /dev/pts                devpts  gid=5,mode=620  0 0
sysfs                   /sys                    sysfs   defaults        0 0
proc                    /proc                   proc    defaults        0 0
/dev/rootvg/swaplv      swap                    swap    defaults,_netdev 0 0

• Changing it to:

/dev/rootvg/rootlv      /                       ext3    defaults 1 1
/dev/rootvg/varlv       /var                    ext3    defaults 1 2
/dev/rootvg/locallv     /local                  ext3    defaults 1 2
LABEL=/boot             /boot                   ext3    defaults,_netdev 1 2
tmpfs                   /dev/shm                tmpfs   defaults        0 0
devpts                  /dev/pts                devpts  gid=5,mode=620  0 0
sysfs                   /sys                    sysfs   defaults        0 0
proc                    /proc                   proc    defaults        0 0
/dev/rootvg/swaplv      swap                    swap    defaults,_netdev 0 0

• This works much better, but is there any problem with not having _netdev here ?