The thinking goes like this ;
1. If you can see who installed it then you can hack all their boards with the crafty back door you incorporated.
2. By posting in the thread the installer is making the decision that they don't mind the author knowing they have installed it (but presumably they are still free to make use of that backdoor ..... ).
Don't laugh - it's all true - those are (afaik) the actual reasons.
Paranoia rules.