They reach across the aisle because they basically never have control of Congress. Dems need all 3 (presidency, house of reps, and Senate) to pass anything. When they don’t have all 3, they have to reach across the aisle to pass anything. So guess how long they’ve had all 3? They’ve had it for 4 years of the last 24 years.
And if they didn’t reach across, guess what happens. The GOP shuts down the government like they did to Obama.
So what can you do move things left? Give Dems consistent and overwhelming victories in all 3 houses.