Why get_buffer can not wait?

[leonp at plris.com]

Hello, all.

The "rtems_partition_get_buffer" has no option for blocking and waiting for 
buffer availability. The manual says:
"...unsuccessful return code is returned immediately to the caller. Tasks 
cannot block to wait for a buffer to become available."
I am interested to understand what is the cause of this limitation, if 
somebody knows...:-))

Thanks for satisfying my curiosity.
-- 
Leon