There's an alternate history in which it was David Miliband who became Labour leader, not his brother. Who knows of course, but there's a decent chance it would have prevented the disaster of Brexit (and the related disaster, for Labour and the country, of Corbyn).
In a sense, I don't disagree. But when the only Labour politician of my lifetime to win an election is Tony Blair, you have to consider that the UK is a pretty Tory country, and you have to work with what you've got...