I assume you're referring to the scene in the first movie where apac unplugs the two members of Morpheus's crew ( i think it's two? i used to be able to recite the whole script word for word lol) while they're in the "matrix" causing them to instantly die?
This is just my opinion but I think it's cus even though they have already been "unplugged" both literally and figuratively from the matrix and understand that it's really just an illusory program set up by the machines to help keep the humans alive (maybe keeping them entertained with some good ass dream resembling reality makes them produce more energy?) while they harvest their energy, while plugged in they can't help but believe, maybe on just a deep subconscious level, that the matrix is real because the program has been designed to be so realistic. Hence, the immediate removal of all information simulation that is the matrix causes their body and brain to instantly go into shock and die. The reason Neo is the one is because he genuinely believes that the matrix is not real and thus has complete control and power over everything in the matrix, e.g., the power to fly, bend spoons, destroy robots at will, etc. But even Neo needed the love of trinity to come back from death which basically sums up the movie's overall theme that love and faith conquers all.