Besides it doesn't make sense anyway. Say you added he discoveryName on the mainConfig.
When you create a connectionFactory through management, you want to reference the discoveryName which will have the ports, config.. etc.
Now say you moved the server to another network (say because of a cloud move.. or something).
You will now have to recreate all the ConnectionFactories because of this.... So, the JMSConnectionFactories should have a reference to the main config and not replicate the information everywhere. Just a simple principle applied to any ER database here.