Are Account Usernames Case Sensitive?

If there's one thing that seems like a bad idea, it's case sensitive usernames. I mean, JohnSmith and johnsmith are 2 different accounts? No, that's just bad. I had thought I saw that usernames were case sensitive, but when I look at my profile, I saw that my username was shown in all caps.

So, naturally, I tried logging in with incorrect case. And I got in. I must have been mistaken when I saw that. But, I decided to start making a second account and got to the page where I make my username and voila!!!!

See that text under the Username box? It says:

The username is case sensitive. Choose a username that is 6-74 characters long and must contain a lowercase or capital letter, a number, or one of these symbols _@/-

I added the italics. Ah ha! I did see that! I'm not going crazy. (Well, I am going crazy, but I did see that!)

But, despite what it says here, and based on experimentation and observing that your username is shown in all caps, the answer is no, the username is not case sensitive.