Of course the cruise lines care. Have you ever looked at the membership list? With that many people reading these postings, to say nothing of the number of non members who we brief on cruising, the numbers could be quite devastating to the future business of a line. The cruise lines read these postings! Personally, we wouldn't post otherwise.
To our knowledge there are no "Hotelmates" postings on the web where companies such as Hilton or Sheraton could receive and withstand such critiques without reviewing them.