Maybe we can agree to disagree about the terminology here. To me if it takes vector inputs and displays them, it doesn't matter if it's pixels on a grid or tiny

Maybe we can agree to disagree about the terminology here. To me if it takes vector inputs and displays them, it doesn't matter if it's pixels on a grid or tiny elves holding up colored signs. It's a vector display. In any case, the PLATO display absolutely did not use "segments", as the OP claimed that it must have. He also claimed that bit-mapped plasma displays "didn't exist at the time".