Every single character being manipulated for decades by some super powerful evil guy was already done in the prequels. And it was stupid.
Turning the whole saga upside down like that would just diminish it. The events of the earlier movies would lose their importance if everything was staged by Snoke. The force ghost of Obi-Wan gave true guidance to Luke, retconning him like that nullifies his teachings. In the context of the whole saga, Obi-Wan and Yoda are already complete idiots for not figuring out that Palpatine was behind it all, now they were also tricked by Snoke, too?
And then, is this plan really the best way for Snoke to rise to power? Like, is there no easier way than manipulating someone to fight against your cult in order to convert them to your cult? Like, why would he guide Luke to kill the Emperor, if the Emperor was the most powerful Sith and the Sith were created by Snoke specifically for his revenge plan? Wouldn’t it be easier to support the Emperor and Vader, who are already converted, instead of Luke, who might get converted, but if there’s a small chance that he doesn’t get converted, it would set the big plan back by decades?
JEDIT: Also, having a plot twist would be a total rehash and ruin Star Wars forever.
The rule of 2 is not lIke the old sith empire. The rule of 2 was less theocratic and more governed by government manipulation. The ancient sith empire built shrines, temples, and sacrificed jedi to him(this is all canon). Kylo ren looks like a freaking templar. revan can actually be tied to snoke. Maybe the threat in the unknown regions was a weakened snoke bidding his time. Snoke is immortal and is in no hurry