Can one have compassion by accusing another they have none

Yes, becuase if the other person truly doesn't have any, then, in telling them that perhaps they will change, so u showed compassion towards that person by hoping that in pointing out their flaws, they will improve.

My experience has been that pointing out another person's flaws when they haven't asked for advice seldom does more than start an argument. The best way to teach compassion is by setting a good example.

We can easily see the faults and flaws in others but it's so difficult to see them in ourselves. Imagine a world where EVERYBODY spent all their time making sure they were doing their absolute best at taking care of their own responsibilities...