Output config usefull only if there is only one item for sending and one value in all config file. 
Otherwise, I need to create many outputs and many if-else conditions in output. 
If there are several of them - this config setting is useless.

For example, when I want to send
from first grok pattern
- [x]  "some data" field value to "first" item

from second grok pattern
- [x]  "message" field value value to "second" item
- [x]  "timestamp" field value to "third" item 

For this schema I need to execude "zabbix-sender" every time with different parameters just in filter.