Chumps insert their initials at the end of email messages

I get that it is important to have an appropriate email signature at work.  People need to know who you are & how to get a hold of you, inside and outside of the company.

But why do some people include their initials as well (or instead)?  Is this some sort of working-world version of Sesame Street?

I’ve found this happens usually when you have written an email to them and they are replying back.  Take this string, for example: