The Democratic Party is more heterodox than the a Republican Party, but it is def more left than in the 90s on a whole host of issues.

Yes, but groups like the DSA - certainly on a national level - would prefer to be (take your pick: a genuine third party / purists / spoilers / profitably visible noisy dickwads) rather than to work to achieve that shift. Politicians like AOC get endless shit FROM THE LEFT while doing good work.