I don't think it's necessarily being so concerned with integrity as to deliberately self-sabotage, but rather that this was a potentially viable strategy 40-50 years ago, and many of the eldritch horrors in party leadership, Biden included, just haven't gotten the message that the situation has changed in the interim. Part of Biden's campaign pitch was that he's worked in Congress for so long and has the relations that would let him reach out to the other side to get stuff passed, and he just gets taken advantage of when trying to do so. The Republicans have long since moved on to a strategy of "Ram through whatever you can while you're in power, and obstruct, obstruct, obstruct when you aren't." They generally aren't concerned at all with what non-GOP voters think of them and their actions, which lets them just bulldoze their way through the process while racking up points with their base for being effective at advancing the agenda, regardless of how hypocritical/immoral they are in the process. Just see Mitch McConnell when Obama tried appointing a justice to the Supreme Court near the end of his term versus his response to Trump doing the same.
I would also say there's just a fundamentally different level of at least the appearance of integrity necessary on the Democratic side, and Democratic voters are less willing to accept that the ends justifies the means. This is clearly illustrated just by looking at the fallout for pretty much any Republican having a sex scandal, versus it happening to a Democrat. In his initial scandal, Anthony Weiner didn't even engage in a criminal act, having sent a 21-year old woman a sexually explicit photo. In less than a month, Nancy Pelosi had called for an investigation into it and he'd resigned his seat. In contrast, Trump has been found liable for sexual abuse in a civil case and has had heaps of sexual assault and harassment accusations brought against him, yet the party of family values, good, Christian morals, and law and order is still completely behind him.