I honestly think that the Dem’s big tent policy from the Obama administration (remember the Blue Dog Dems?) has caused them to become infected by ‘temporarily embarrassed Republicans’ who have slowly but surely used their money and influence to shift the party rightward.
Think of all those ‘Never Trumpers’, and where they’ve wound up - hell, Kamala was spruiking Liz Cheney!
Australia is going through its own self-destruction of our mainstream right-wing party - but at least they had the good graces to split into their own loose coalition of ‘independents’ (Teals) instead of infecting our Labor party.