[Boy is she. Edelgard can tell this has suddenly become a more personal thought exercise than she had intended. So, she's quick to seize on any certainty that Leslie has and encourage that rather than let doubt plague her.]

That is typically something that is the aim of more subtle attacks, yes. To remove a single person, the rotten egg in the bunch, without having to harm their soldiers or underlings.

Very rarely is it used indiscriminately, and that is not something that I would encourage or condone. People deserve the chance to thrive, and such tactics are best employed like a physician's knife, against those that would deny them that chance.