Realtime Render

Whats the purpose of realtime song render in 2.7? Im shure i dont understand something here. Isnt it must be a true real-time render or better say recorder - while the song is playing i do my mangle-trigger-fx stuff. Right?

Sorry everybody, but i reeally dont get it. Help.

When catching a remark from Taktik in the Virus TI topic recently, it seems the realtime render mode was also implemented to support the Virus TI better.
Along with the wish to record output from external synths through the line input device it was a must have addition.