QC as a separate step is pretty useless because the last person to touch the ep should be watching most/all of it anyway. Whether as an editor checking for flow, an encoder checking their hardsub, or even a timer making sure everything snaps to scene.
It doesn't exactly take much training to notice typos or missing lines, so the only way things should slip through this is if everyone involved is being passive-aggressive at each other re: "not my problem".
About the only use of it is catering to staff laziness or scratching the ego of someone who can't even time by letting them feel important anyway.
On a side-note:
Groups who release karaoked textless OPs/EDs.
syduck: