Um, well, like I said, maybe they didn't realize it wasn't really their account.
I did something like that, just not to someone else. I had an old account, which used to be my main until I left for a while. When I came back, I couldn't remember the password. What I also couldn't remember was the email I'd signed up for it with, and that that email had been deactivated due to inactivity.
So, at those random times I felt like trying to get back in, I'd keep sending password requests. The prblem was that, even after I remembered the email address, I didn't realize that I was sending the password request before reactivating my account. I usually sent the request, then when I went to check the email realized it was deactivated again, then reactivated, but the email wouldn't have gone through, heh heh.