>the dispatchers can not request certain signals. They only request for a route to be lined. Nothing shows up on their board regarding the signal aspect, only lined or not lined.

This has been essentially true for about 10 decades, if you include interlocking towers -- CTC is just a bunch of mini-interlockings inserted into an ABS system. The operator (or DS) clears a signal (lower case "c") whether the signal actually goes Clear (upper case "C") or displays some other permissive indication is dependent on conditions in the field. This "request" term derives from the relatively recently introduced computerized interfaces which the operator/DS uses to control the interlocking/CTC equipment; the operator "asks" the computer to do the work.

I've never heard of a track model board, whether a real one or a CRT/flat panel monitor, which doesn't show whether or not a signal has been cleared (lower case "c"). The disappearance of separate levers to control particular signals began with the introduction of NX-style interlocking in the 1930s, in which you marked the beginning and end of a route and then pressed an execute button.