it is physically impossible for Snoke to have kickstarted the entire dyad because according to Kylo, the effort of such projection would kill
Are you referring to when he tells Rey the effort would kill her? In the theater when Snoke revealed he did it, and when Luke later died, my assumption (and I’m sure the writer’s intent given the Dyad didn’t exist yet) was simply that projecting your image into reality for all to see is far more of a strain than a mental link between two people created by a third person. Snoke was using triple the “processing power” for his feat that Luke was, having not only his own mind at his disposal but also Kylo’s (because he’s been in his head for years) and Rey’s (possibly because Rey and Kylo were in each other’s heads in TFA).
There’s also the possibility that Snoke himself was just more powerful than Rey or Luke, and that he can effortlessly do things they can’t. But I know implying that anyone could possibly be stronger than Master Luke is a sore spot for certain fans.