It's possible, but impractical IMHO, which might be why you don't see people doing it. Might be a good strategy for keeping various personal cuts alive on a single mother plant with restricted plant counts???
I suppose what I'm trying to get at is,,,,,,,,,,,,,,,the life span of most cannabis plants is so short that any usual benefits of grafting would be totally outweighed by the stress(and recovery) of the actual process.
Edit........wanted to add.........not sure if it's possible with other genera, such as hops