The teachings you referenced were actually a big help for me in my efforts to be more compassionate. The best I can do with "fools" is lead by example, and not become attached to a certain outcome with them. I can be present, comforting, provide guidance when asked, but I should not expect a leopard to change it's spots. For "fools", compassion is more like drops is a bucket, it might take a awhile to fill up.
An example: A coworker of mine is an awful gossip. I have suggested to her that she should be careful with her words, but that did not result in any change. When I learned that I was the subject of her gossip, and she was telling lies about me, I confronted her directly. She made excuses for her behavior, but she is still a gossip. Now when I am in the lunchroom and she is there, I engage her in pleasant conversation when I can, but the moment she starts in on the gossip I excuse myself. Other coworkers have started to follow my example. If I remained obsessed with "helping" her, I would only become frustrated in my efforts.
"As I am, so are others;
as others are, so am I."
Having thus identified self and others,
harm no one nor have them harmed.
Sutta Nipāta 3.710