I read the title as impedance, then I read the article and kept reading impedance, and was about to write a comment mentioning that that's not at all impedance

I read the title as impedance, then I read the article and kept reading impedance, and was about to write a comment mentioning that that's not at all impedance he's talking about, it's idempotency, but then I read the title again and now I can't understand why I read it as the former all that time.