Those who blamed the Gore loss on Nader were right on point, and that TRAGIC mistake has had so many deadly and costly ramifications. Nader ran on scummy lie, that "there's not a nickel's worth of difference between Bush and Gore". Tell that to the hundreds of thousands who were killed in Bush's stupid war, or to the dark money plutocrats gleefully taking advantage of Citizens United, or to women when Roe is overturned next year. or to the billions who will suffer from the eight years of Bush inaction on climate change.
Sanders damaged Clinton in the primary with endless insinuations of corruption, and I guess all's fair in love, war, and politics. Doubtful in the extreme that Sanders would have beat trump but then we'll never know, I just hate seeing "the left" taking their eye off the ball time after time, a lot of regular people get hurt as a result.