@porurun You know, accepting criticism and feedback to help grow as an author is one of the points of being an author. Telling people they can't be disappointed or not like something just because someone created it is both not helpful in general and potentially harmful to the creator as it removes necessary feedback.
Authors and other creators cannot develop in a safety bubble created by overzealous fans like yourself trying to shut down honest criticism and feedback. So kindly reflect upon your decision to yell at someone for posting their opinion on the manga and thus provide a source of feedback and please stop trying to force others to not voice their criticisms. You are not the author's knight errant, so put down your sword and shield and take part in the discussion like everyone else.