Obama was despite the democratic party. I'm not sure why you're including the average voters here because they are not part of the Democratic party machine.
But if you want to include the voters let's. The fact is among registered Democrats Biden running again is very unpopular.
No Democrat is going to run against Biden after he's declared because it would weaken his candidacy even more against the Republicans. I think ultimately Democrats want to defeat the Republicans, and primarying Biden is the best way to weaken the entire party. You repeating that so matter of factly is just silly.
If people can't see that letting an incumbent like Biden at his age and with his numbers, even among his own party, be the automatic selection is not being dynamic then I don't know what to tell you.
You should get a job fundraising for the Democratic machine. You'd fit right in.
I'll run for some school board to effect national change, but you first. Then, we can surely hand pick the next POTUS.

Not sure why you had to get salty, but whatever. We generally have similar political viewpoints. I've said in other threads that I'm not confident in 2024, but there's a long way to go. Biden's approval ratings speak for themselves, and generally you can't win reelection with a number below 45%. He's still polling decently in a hypothetical rematch vs Trump, so no sense in smashing the panic button today.
If the thesis is that Biden is too old, unpopular and not a good candidate, then a "dynamic" one should have a shot at beating him, no? Basically, you're upset he's running again, so that's not really the Party's lack of dynamism is it? Did the party insiders force him to run? You're arguing both sides, that Biden isn't good enough for you but that nobody else should throw their hat into the ring either. My point is that if there is a strong candidate out there to defeat DJT (or Ron Death Santis), I'll give them a real look. I already said I don't like Newsom or Whitmer's chances in a general election, and I have nothing against them! You rightly commented that Whitmer could do well in the critical Rust Belt.
Biden hasn't been perfect, but his administration has generally executed well prior to Dems narrowly losing the House. There is a large disconnect between where the economy stands and how the electorate views the Biden administration. That is the challenge that must be solved to win reelection. Obviously we're both concerned about this, but I'm a voter and not a political strategist. It's maddening how hard it is to convince the electorate of what seems obvious to you or me, but that's partly because the Dems are a big tent party while the GOP basically caters to easily fooled rubes. Unfortunately for us, you can mind fuck a lot of people with culture war nonsense (layered on top of "voodoo" economics) these days. If the messaging problem was easily solvable, we would have done it by now and winning presidential elections wouldn't be hard at all. I'm not trying to change your mind about Biden; and I recognize you've already said you will strongly support the Democratic nominee next year.
In a vacuum, I'd prefer not to have an octogenarian running for President but it is what is it. For me, his health and vitality are more important and I believe he's still in good shape (for his age). We won't know for sure until next summer. He takes way better care of himself than the Donald, who is just a few years younger but nobody gives Trump so much shit about age because his base actively supports his sexual indiscretions. If voters are genuinely concerned about a POTUS having a heart attack on the job, they should be very nervous about electing Trump. As an aside, although Trump isn't the sitting President, he's basically the GOP "incumbent." Yet nobody is whining that RDS or Tim Scott et al running weakens him for the general. Instead, it's all wild mocking of RDS's lackluster campaign.