Brown was not Blair , and that stated this rot , you've carefully selected the dying Blair / Brown era ,as your rightly point out the Miliband and Corbyn vote share rose , strangely they never found power.
Think the Corbyn defeat was the worse since 1935 for Labour and even after that they and you still cant see through the fog of the past ,they should form their own fringe party and allow Sir Keir to invite in and back the centralist and get elected its not impossible its about removing the part of the party that holds it back .
'Lose, lose, lose, lose, Blair, Blair, Blair, lose, lose, lose, lose’. 11 true and sad words
But hey, you know all this.