You may be stunned and astounded to discover that This Actually Happens.

(Examples include both Gmail and other systems.)

<https://news.ycombinator.com/item?id=12025091>

<https://news.ycombinator.com/item?id=12027598>

<https://news.ycombinator.com/item?id=17284211>

<https://news.ycombinator.com/item?id=36756201>

There are horrible people who loves the idea of being able to use someone else's identities. Not just made up but stolen. I - I don't want to know why, nor what they're normally thinking.

How would dot sensitivity prevent that?

In my case, a few years ago, it was a user who didn't understand the difference between Twitter and Gmail.