A confidence repeated anonymously may still be recognizable to the people who know its setting.

Taking the name out of a story does not remove the person from it. Anyone who knows the setting can reconstruct who it was from the details you kept in: the job, the timing, the specific thing that happened. So a story told as if anonymous is often perfectly legible to exactly the people it was most important to keep it from. The teller feels careful and the subject ends up exposed anyway.

Before repeating something, ask whether someone in that room could work out who you mean. If they could, the choice is not between naming and not naming; it is between telling and not telling.