“We’ve become a Dyad in the force” is good enough for me. Snoke bridged their minds, already an unusual thing in the force. That was inadvertently the catalyst which formed the Dyad. Snoke and Palpatine didn’t know it would happen. Snoke thought he made up their relationship, but it was so naturally incomprehensibly powerful, that it continued beyond his control, and lead to a full on mystical Dyad. It’s basically a coincidence. If Snoke hadn’t bridged their minds (which is JUST them force skyping and seeing their surroundings), a Dyad wouldn’t have happened. Transfering items and having enough power to handle having their combined lifeforce sucked out of them to restore a body full of thousands of generations of sith… and still have enough energy to both get up from that… is what their Dyad is. (As well as healing each other, but that’s just my head canon.)
It still works this way for me, and it’s important to have Snoke do something in 8. Because he doesn’t do much else besides this, lol. Snoke is a fool and his downfall was thinking he could manipulate Rey and Kylo, I suppose.
I understand the want to get rid of this, but i like the mystery behind it. There’s just enough there for me to understand it enough without it being confusing. (although ironically, this is all rather confusing.)