Damir There’s a great book you should read called “Change your words, change your world”.
The problem here Damir, is the WAY you deliver the msj, you lack empathy for Peter’s efforts, your heart is in the right place but your words aren’t….
Writing a msj using polite word's is free, and I’m certain the feedback you will receive from Peter and the rest of the forum will be 10x better.
Technically the word “Useless” is that it doesn’t have a practical use…. And in another context it will be ok to use it, but you are referring to somebody’s work, and it can be hurtful to use it…. Try instead offering a solution, or just say (I think it would work better this way) the msj is the same and you are exposing the issue, and offering a solution without being rude.