Benefit of hindsight. How many people has Boris proclaimed his friend only to say they never were his friend only a few months later?
The Tories have been pretty blatant in blaming all those events (apart from Truss) for being shite haven't they?
Is that all that matters? Wouldn't it be better to have someone who didn't win as convincingly but was able to offer meaningful change with a smaller majority or coalition partners?
The Tories are right that those issues have affected the economy. They've also done plenty of other stuff that was entirely their fault, Truss is a Tory, and arguably the "cutting the green crap" made us more vulnerable when energy prices went up.
The assumption in your last point is that he's guaranteed to win whatever he said. Remember that he came in as leader 20pts behind in the polls, and at various times since the Tories have had leads. How do we know that his original pledges would have got him anywhere near where he is today?
And surely any coalition is likely to end up with a blander offer than his pitch to members? It's unlikely that the Lib Dems or SNP are going to be dragging a Labour govt further to the left.