How can they claim "data protection" in one case and make it mandatory to put your name and phone number their in another?
It makes me very uncomfortable to host a website, when I know I will get spam, unwanted telefone calls, maybe even unwanted visits at my home, etc.. And it deters me from posting something even a bit controversial on my own domain - this is probably an intended side-effect of the "impressum" policy.
(* well, German law, but there is likely something similar in other countries)