Its the whole Labour thing in a nutshell. Follow the protocol, regardless of how stupid the outcome. They've just completely forgotten that politics without power is pointless. Corbyn is a good guy but he's not a winner. Then you look at the other choices and realise he's far and away the best guy they have, Thats the really depressing bit.
As for having a leader that 80% of the MP's don't support, it reminds me of the Not the Nine o'Clock News sketch of the Union bosses ordering tea or coffee, where everyone orders tea, but then one of them says 4m votes for coffee.