It seems that this move is largely a symbolic measure that was pushed for by the Bernie wing and generally opposed by the establishment, particularly the black leadership. My assessment is that it won’t predictably help the leftist faction, though, but will merely introduce more chaos and possibly even more elite control into the process. I do favor the introduction of absentee ballots for caucuses, however.
The new rule states that superdelegates can’t vote on the first round if someone has won a majority of pledged delegates during the primaries – IOW, the supes can’t steal the nomination from someone who won a majority of the vote (Almost certainly…it is theoretically possible, as DinoR points out, that someone could win a majority of delegates without quite getting a majority of votes cast). I don’t see how anyone could possibly object to that.
However, it’s not uncommon for nobody to win a majority, and that’s where the potential problem comes in. If there’s no first ballot majority, then the superdelegates get to vote on the second ballot, at which time most of the pledged delegates become unpledged and can vote for whoever they want. So there could then potentially be two factors that could work to the advantage of the candidate(s) who didn’t win the most votes. If the problem is that the process is perceived as undemocratic, I don’t see this as being a fix.
There’s no perfect system, and reasonable people may disagree on how much influence elites should have. I assume we can all agree that if Dwayne Johnson gets 50%+1 of primary votes cast, he should be the nominee. Likewise, if the primary vote ends up Sanders 49.6%, Biden 49.4%, others 1%, I assume we can all agree that the 0.2% margin shouldn’t be decisive and some sort of role for party elders in breaking the virtual tie is appropriate. But what if it’s something like Sanders 40%, Harris 25%, Biden 20%, Booker 15%? IMO, Sanders should be the nominee, but OTOH you can argue that he didn’t come close to winning a majority.
What if we assume that polls show a majority of the non-Sanders voters would prefer any of the other three over Sanders? Would it be a relevant consideration if Sanders’ large plurality consisted almost entirely of white voters? Should polls comparing the candidates’ relative chances in the general election be taken into account?
I think there should just be a simple and straightforward rule that ensures a candidate will win the nomination not only if they get a majority, but also if they get a decisive plurality. Say, if the leading vote getter gets at least 35% of the vote AND beats their nearest competitor by at least 10%. If that doesn’t happen, the convention has to decide, and determining the precise balance of power between voters and party leaders that should exist in that situation is above my pay grade. (It would be even better to use ranked-choice voting in the primaries, but that’s another thread).
Consider the scenario I outlined above, where both Sanders and anti-Sanders forces would feel strongly that they had earned the nomination at the polls, and whichever side came out the loser after the convention shenanigans would go ballistic. If everyone had gone into the process knowing exactly how well they had to do at the polls in order to avoid casting their fate to the convention, they would hopefully at least not go quite so ballistic if the process didn’t produce their desired outcome.
Ultimately what the party needs isn’t a particular set of nominating rules, but an atmosphere of mutual respect between the candidates and their supporters, and a willingness on the part of all sides to put the primaries behind them and unify behind the nominee. I worry that, on the whole, these new rules make it more likely that a situation will arise in which maintaining those attitudes will be harder than it needed to be.