Not being able to reread the partition table - why is Linux so 90x?

["Artem S. Tashkinov" <t.artem@lycos.com>]

Hello,

I wonder why in 2013 I still cannot modify _unused_ partitions on the fly,
yeah, the Internet is full of:

# hdparm -z /dev/sda

/dev/sda:
 re-reading partition table
 BLKRRPART failed: Device or resource busy

# fdisk (after adding a new partition using unused space on my hdd)
...
Command (m for help): w

The partition table has been altered.
Calling ioctl() to re-read partition table.
Re-reading the partition table failed.: Device or resource busy

SCSI rescan command doesn't work too.

I do understand that the Linux kernel doesn't have any form of invoke() but
then it prevents me from altering the partitions which are not used - it's
100% counter intuitive. Windows, for instance, allows to modify even a
system partition on the fly since 2006, Linux doesn't allow to add partitions
without rebooting the system.

Could anyone elaborate, please?

Best regards,

Artem