This isn't in fact total nonsense, although it's expressed in a confused or misleading way. What "our" political system needs isn't an effective opposition so much as a _sound_ one: a backup govt that challenges points of detail but accepts the basic principles of state policy https://twitter.com/bbclaurak/status/1246380641270235137

Labour under Corbyn got more votes from the general public than it did under Miliband, inflicted more Commons defeats on the govt, etc; effectiveness—by any identifiable metric—isn't the issue at all

But Miliband Labour was sound. In a pinch, it could have been called upon to form a government & you'd have been entirely confident it wasn't going to do anything to upset the City or the arms industry or the White House. Corbyn Labour (rightly or wrongly) was not seen as sound

And in that sense Ms Kuenssberg is right. The British system relies on the opposition to the sitting government not being _at all_ oppositional towards the state & the ruling class. If that loyalty wobbles, even a little, things soon get awkward. Even the BBC has to take sides!