No blackmail possible if you’re not a sleaze bag.
You don’t need to be a sleaze bag, all that has to happen is someone who is bigger and intimidating has to say to you “Nice family you’ve got there, it would be a shame if something happened to them.”
I don't think they allow much support or money to go to people who are not sleaze bags. If they have leverage over you, you might have a political future. If they have no leverage over you, you aren't going anywhere. That's why Trump frustrates them so much -- he's the miracle that wasn't supposed to happen.
“No blackmail possible if you’re not a sleaze bag.”
And hence why the powers-that-be make sure sleaze bags get promoted in the Democrat Party and Washington, in general.