Such as? Can you be concrete? I don't know which of these privileges you're talking about that people will hold onto if they're even hypothetically leftist. Who is the person out there saying "I want to vote for Bernie Sanders, but if we start holding police officers more accountable, I will be losing something, so we now have a point of conflict." Who are these people and why do you know them?
Police action won't affect white dudes, sure. But how about affirmative action? I strongly support that, and in fact, I think it doesn't go far enough (white women disproportionately benefit from it while people of color don't get enough benefit). But I, as a white guy, may end up not getting a job over someone who is equally qualified but is a person of color. That's a good thing on average!
And this is also a benefit that most white people don't know they get; nobody hires somebody and says, "I'm hiring you because you're not one of those people." They just don't notice their own biases (or don't publicly state them). I've probably gotten jobs before because of racism (and hell, this is rural Mississippi. I'd bet my bank account on it).
Racism, sexism, discrimination in general; all of that benefits me as a cis-gendered, (mostly) straight, white man. And of the few things I'm not socially privileged on (my religion), I can hide that easily. My fight for social justice will cause me to lose things, for sure. But I gain in cultural diversity and I gain from belonging to a more equal society. My overall point in that post is that not everyone values that as highly as I do, and so if the time came to, say, reject an economic program because it excluded a minority group, I'm not as sure that people with heavy economic interests will reject such a program.
I truly can see both sides of this argument. We had a fair number of pro-life Blue Dogs as recently as 2010. As far as I can tell, they exercised little influence on the party's position vis-a-vis abortion. What reason do we have to think that they would this time?
But for once, I also agree with PBY. Abortion rights should be fundamental in a liberal democracy. You may not agree with abortion personally (Kaine, Biden), but you cannot limit women's ability to dictate their reproductive - and, by extension, their personal and economic - lives. We should be sending that message consistently and vociferously. Accepting pro-life candidates, even if they have little hope of gaining power, can be construed as a dismissal or marginalization of women's rights, a subject on which we should never compromise. Appearances matter, especially in a party comprising so many vulnerable people who depend on Democrats to defend their rights.
Let me phrase it more concisely: were I a Democratic strategist, I wouldn't court these candidates.
To be clear, I agree with this position. But I also want it to be known that it is a compromise to me. I do not think abortions are bad. I don't even think it matters whether a fetus is alive or not. To me, the right to bodily autonomy should trump all else in the conversation, in a sense. But I accept some compromise in this, which is why I'm okay with people not carrying that message. My limit still exists, and that limit is advancing actual legislation.