They have buddy-buddy dinners with each other all the time lol. This is not a serious power struggle to them.

Since 1980 there have only been 3 periods where Democrats have had solid control of the House, the Senate, and the presidency. The first was under Clinton, for 2 years, where they rammed through a number of right wing bills (that Genocide Joe helped with, like the Crime Bill and NAFTA). The next two were the ones you refer to, where Democrats adopted their excuse-making strategy rather than actually hold clear lines. And because the Dem base is domesticated, they learned to parrot those excuses rather than organize to demand policy.