Because season 12 has been incredibly referential (and reverential) to the ones that came before.
Weve had the return of the Colt and the alpha vampire.
Weve revisited the poor, doomed sons of Crowley and Rowena.

Credit: Dean Buscher/The CW
Weve examined Cas journey on Earth and why Marys struggling to find her place in the Winchester family legacy.
First, the heavenly part.
Cas wordlessly grabs the recording and bounces.
Now, to the Hell part, where a couple is camping in cold and damp Nebraska.
(For you, Hell may be other people.
For me, its camping.)
One state over, the Winchesters are returning to the bunker after a lengthy road trip.
Dean swaggers in brandishing a barbed wire-wrapped baseball bat and declares, Dad loved this thing.
Then Sams phone chimes with what he says is a program he designed to alert him about potential cases.
Computers: monsters, porn, is there anything they cant do?
Honestly, there was more domesticity in that one little scene than weve gotten in entire seasons.
Hi, my name is Sam Winchester, and this is my much handsomer brother, Dean.
But you, youre cool.
And since theres nothing around for us to kill, peace out.
Unfortunately, the hellhound slipped inside the house with the Winchesters.
Dean gets a shot off getcha some hound revenge, buddy!
and it dives out the window.
Like, I dont know, a Hello Kitty backpack, or the death of an enemy?
She says no and doesnt think Marcus made any deals, either.
Gee, where can they turn for answers to not-so-common hellhound questions?
Aaaand cut to Hell, pt.
Then theres a knock on the door, and Crowley muzzles Lucifer to meet with his minions.
(Another is tort reform, to the amusement of the lawyers in the audience.)
Now shes loyal only to Lucifer, and Crowley would like her head on his mantle.
Also, he explains that Ramseys gunning for Gwen since Gwen whacked her with an axe.
Sams with Gwen, and Dean tells him to be careful with her.
But of course, he means Baby.
Just imagine shes a woman.
A beautiful, beautiful woman.
and, you know,fixing Cas.
Crowley replies that he was just sparing himself from Winchester Man Pain (ha!
Hi, additional fourth-wall hijinks!
), and since Deans working with the king of Hell, maybe I rubbed off all over you.
This gives Dean the full-body heebies.
In Baby, Gwen asks Sam to pull over so she can puke.
(Thankfully, she spared the upholstery.)
Awww, who was a good girl?
Yeah, definitely not Ramsey.
NEXT: Lets make hell great again
But he returns home to treachery.
Once hes freed, he does some amazingly goofy stretches, then poofs Victor out of existence.
My life is yours to devour.
See, now you just made it weird, Lucifer says before poofing him, too.
Mark Pellegrino is the best Lucifer, period, full stop.
So anyway, now Crowleys back, and he finds Lucifer sprawled on the throne.
But not so fast, Lucy.
Crowley snaps his fingers and in a blink has Lucifer gasping in pain on the floor.
And even after that, Imstilljust getting started.
Heres your periodic reminder that, in fact, Crowley isfrightening.
Okay, Heaven time again.
No, Dean corrects.
But Sam argues that the BMOL save people witnessthe death of the Alpha Vampire.
Neither would be easy to take, particularly coming on the heels of Mary doing the very same thing.
And the episode ends with Sam accepting Micks call.