Corbyn was unelectable due to the awful media campaign against him and his lack of electoral nouse. Policies mean nothing if you are seen as an unlikable, antisemetic terrorist sympathiser by low interaction swing voters. Truth is irrelevant.

The shitshow media will rip apart any proper socialist leader. Maybe someone with a better understanding of how the media works and who is generally more likable could convince people but who would that be in current Labour party?

I am proposing an electoral alliance. I don't think a Labour majority is remotely realistic in the UK. It wasn't before the SNP rose (Blair is the only one who managed it and we all know that wasn't real Labour), now it's totally impossible. Given that reality, supporting PR and an alliance with the other parties on this issue to win an election is the smart move. A coalition of the left running the country is infinitely preferable to another 10 years or more of the Tories, which is where we are headed if this infighting and naive idealism isn't dealt with.

You say this isn't pragmatic but it sounds like all you are suggesting is more of the same failed approach. Change the players but keep the game the same. It's not worked for 5 decades, what makes you think it will now?