I agree, it’s an oversimplification. The Democratic party has become the party of ‘going back to business as usual’ and refuses to lower it’s commitment to the corporations that fund it. Trump won 2016 because he was a genuine establishment shaker.
Leftists need a rouge candidate who refuses to bow. Someone who shows promise of CHANGE and not business as usual.
A lot of people criticized Dems for exactly this when Harris was appointed after Biden dropped out.