Miliband appears to have overlooked his own culpability for this fiasco. Firstly, in 2015, he lost a general election he could, and should, have won.
Then he enabled the hard Left to take over the Labour Party by changing the rules on who was entitled to vote in leadership elections. His ‘three quid to vote’ scheme allowed mass infiltration by both Trotskyites and Tories, resulting in the useless, unelectable Corbyn becoming leader.