I agree. I think the target was a "type", also. I also agree it seems unlikely it's the killer's first murder. What I do believe, however, is that the killer is close to the same age as the victims. I feel it's likely this person had an obsession with this type of crime, and with serial murder in general, and expressed that interest thru an immersion in single-killer computer games, and a hero-worship of people like Ted Bundy, Danny Rolling - who used a Ka Bar in his murder spree - and Israel Keyes, among others.
I also find it fascinating that the knife attack of the couple in Salem OR, in which the husband was killed - happened around a week from when classes began at U of Idaho in 2021. What if this was the killer's first attempt, and it had been unsuccessful in his eyes, as he left the wife alive. Perhaps he left for school right after the attack, and became loosely acquainted with the King Rd group. I've seen some TikTok video of a party at King Rd, one year to the day before the murders in 2021; also three months to the day after the Salem attack. Perhaps he attended that party and felt slighted or dismissed in some way, and he decided to make the house his target, one year to the day later. Sometimes dates are important to these guys.
I dunno, there are so many gaps in what we've been told about that night, the 911 call, the crime scene, that I'm just spitballing here. It sure feels like LE is rather stymied, with the FBI revisiting the house and all.