I have to disagree with your assessment that all poltergeist are a manifestation of the subconscious of (mostly) adolescents.
As you know, ESP depicted in movies is very dramatic. Though on TV heavy objects are moved great distances, in reality and in the lab, PK is often barely detectable and just over the statistically significant line. I can see how intense anger during an argument could cause a sudden, isolated incident (an example would be the famous argument between Jung and Freud) but to have the subconscious perform dramatic, consistent, even intelligent-like acts is a stretch. And from a psychological perspective, people with disorders of the subconscious such multiple personality, almost always direct it inward, not outward.
There is also a popular theory that spirits get their energy from the atmosphere (hence the cold spots) and from other people, especially emotional, sensitive, ungrounded ones (adolescents come to mind here). So you could make an equal argument that says spirits are attracted to teens, not that teens are creating poltergeist.
Many people site the "Phillip" experiment when arguing that poltergeists are formed in the mind. But ask anyone who has used a Ouija board and unintentionally invited in a nasty spirit that they will tell you anything you want to hear to stay close to you. So was Phillip a creation of the participants, or was he a spirit playing a game with willing participants?
The fact is, for every argument for the RSPK hypothesis, there is an equally valid argument for the spirit hypothesis. This is the nature of the study of the mind, whether discussing the normal or the paranormal.
I do not believe we should state the "poltergeist as RSPK" theory as fact; it is too dangerous. Most non-human hauntings begin as poltergeist activity and escalate from there. To dismiss this activity as RSPK is to allow the entity to flourish and to create fear, doubt and self-recrimination in the adolescent, which in turn can open him/her up to at least being the focus of the non-human attacks, and at worst full-out possession.
Since there is no way to prove either hypothesis, I think we should keep an open mind to all possible explanations of poltergeist, since to ignore both sides could be regrettable.
As an aside, it is interesting that you use Hans Holzer and Brad Steiger as examples, two researchers who, to my knowledge, do not believe the RSPK theory. I would also like to recommend Poltergeist by Colin Wilson. Brilliant man, though he does get off topic a bit. I believe it is the definitive work on ghosts, haunting and the power of the mind.