I don't think that's always true. Not long ago, where I work, a dying teenager was in the ICU. A steady stream of mostly kids were coming in all day long to see him. However, I believe only his family were with him when he died, and the friends were in the waiting room.
You are right! ICU and the visitor situation has been a hot item in the medical community. Some have rules more rigid than others. But today we have family centered care and ICU’s have had to adapt to the theme and flex the rules. The environment in the ICU as well as the ER is more restrictive because patients are in high level of medical intervention. But believe me if you are a homosexual partner or significant other you will be treated as family member. Not everyone has family support and we know this in the hospital field. We make accommodations and we prefer patients to have the support of those close to him/her or her/him-sometimes it is hard to tell the difference in places I have worked!