It might now be considered to signify that, but that was not the reason they were originally put in; it is an overlay.
I find the article “interesting”, as there is a tendency among some to imply that without an altar rail, there is less reverence.
My parish has no altar rail; but it does have 25 years +/- of Perpetual Adoration; two women have joined orders (which wear recognizable habits); three men have been ordained deacons; two (or possible three; I forget) ordained priests, and one current seminarian finishing 1st year Theology; and the first parish in 40 years to start a Catholic grade school.
Altar rails are not necessary for an attitude of reverence, or to enhance reverence. An active parish prayer life will do that every time.