Based on this description, it sounds like someone walking past your unattended desk and bent on disrupting your day but not stealing your data, could enter in a garbage password into the lock screen a few times and lock you out of your own laptop.

I guess the same also works for cloud accounts as well. I remember, back in the mid-2000s, trying to log into my hotmail account (never having failed to log in before) and getting a "locked out due to too many bad passwords". So someone, only knowing my user account name (which was the same as my email address), locked me out of my own account. The problem was, I couldn't remember what my recovery accounts were (I eventually figured it out).