I agree with a lot of this and whatever anyone believes, the only way forward is positively and without the rancour. That’s the reason I think it’s time to move on from this constant repetition of that failure. I don’t think many people are still driving that argument forward, they don't appear to be doing so in Labour anyway.
I do take issue with the somewhat passive notion that left wing blame is such an important factor driving people to the right. There is a large proportion of working class people who have not been culturally Labour since immigration in the 60s and 70s. Economically they may want similar things, but their scepticism of socialism and left wing views is very high. Brexit was a defeat of socialism to some, albeit forms most here wouldn’t recognise as being it, the EU, metro liberals. It provided a growing confidence to some hawkish views that are not restricted to a handful of fash. My sister, a kind and normally rational person, shares ridiculous posts on facebook saying that it is not allowed to celebrate Xmas anymore (guess who would be offended) and defying anyone to take her poppy off her. This stuff is absolutely widespread and between this, the Daily Hates and bigoted middle class opinion formers it's an uphill battle to convince people we are on their side. I don't think it helps just saying how horrible we are day in day out. People will just believe it all too readily.