No one is saying he raped anyone, that I gave seen.
I and another poster were discussing possible thoughts in BK's head. Pure speculation. We're all pretty familiar with this case and it's clear there was no rape. Indeed, it seems as if early LE statements implied there was no sexual crime at all (there are other sexual crimes besides rape which leave evidence).
I'm not sure how you would know whether he was thinking only about murder or possibly thinking about sex crimes and murder. Both types of criminals exist, which was my point. This is a very unusual crime. It is virtually the only crime of its type in the Mass Murder Database (most are either ideologically driven OR the people are known to each other - usually family related, but sometimes neighbors or colleagues). There are vanishingly few stranger mass murders in which there's also a home invasion (a house not lived in or previously visited by the perp). We have also speculated here about whether he had been in the house before (if I had to bet, I'd bet that he had been in the house).
We are not talking about an actual rape. We are talking about his mindset, possibly his worldview, his mentality, his motivations. I personally agree with you - that the motivation was either only or primarily rape. But I never narrow down to one hypothesis until there's more evidence. We simply do not know what was in his mind. I have personally interviewed criminals who had the intention of raping, found that to be impossible/not what was going to happen and switched to phase 2 (which was murder, all along). Many rapists DO murder their victims, usually because they think this removes a witness.
I can envision, as I said, a mindset in which a potential murderer also considers rape and is mentally aroused by the juxtaposition (especially as he's driving around, getting ready). None of us knows.
We are just speculating. Some people feel strongly that knife attacks are closely related to sexual attacks. SG's description of KG's wounds makes me think there's a possibility that there was a sexual element to the crime. In BK's mind.
I think discussing possible motivations is crucial in all crime cases, it's the main reason I study crime. It's the main reason many of us are here. I do not at all think the rape scenario is as ridiculous as all the other things you mention.
I could actually reshape the "rape" hypothesis into more words and point to some research about what goes on in the minds of rapists, but I've probably said enough. There are different academic theories on all of this, of course, but there is literature to support the fact that knife attacks, by a man, on a woman, may have a sexual element.
Let me ask you a question, though. Do you think he would have entered a house that had 4 men living in it, and killed a visitor who was a woman, while leaving 2 men alive? I believe he was targeting the house because he knew young women dwelt in it.
If he had killed 4 elderly people, yes, I'd be pondering whether he had something against the elderly and would regard it as a crime against the elderly. That's not what he did. He killed 3 women, all of whom had an outgoing, active, beautiful social media presence, with lots of male admirers (judging by the pre-murder instagram interactions and other clues from the internet).
This was a crime against women, IMO. It's just an opinion. We may never know. I doubt he'll take the stand. I doubt he'll write a book. I doubt he'll be interviewed.
All IMO.