They leave it up to debate because they realize that their dyad idea is contradicted by Snoke having created the mind link. So they basically took a step back and were like, “Well, Snoke’s thing was completely different even though it’s the exact same concept of two people being really close. But the dyad is just the material exchange and the Palpatine rejuvenation juice.” Thing is, that distinction is never suggested in the films and it just makes the concept even more confusing.
Gah just end my suffering please.