At least when Obama promised in 2008 that he'd end the "war on terror" and implement universal healthcare if elected, he didn't have a decades long legislative career showing that he was probably lying. Joe Biden spent 30 years being one of the most transparently racist warmongering reactionaries in the US senate before being rebranded in 2020 as "Obama's fun buddy" and "the most progressive president in history". No one who wasn't a literal child at the time can legitimately pretend that this is some surprising betrayal.