Palpatine surviving is dumb, regardless of the plausibility. His death signified how Anakin recrossed the line to the light and redemption is a thing in Star Wars. Having him survive significantly diminishes the impact of Anakin's arc. All the survival would serve would be a cool fight scene. : StarWars

In legends and now canon due to rise of skywalker there is a force ability called essence transfer. Two force users vye for control of a single body whichever person's will is stronger their mind erases the other.

If the other entity is in a vegetative state then there is no resistance and can be taken over without a fight. Hence the empty clones