I think its to give it a finished look. Also when pounding down the feather strip I think they use the edge of the rail as a guide this way they dont hit the rail top. The never think of what it does to the cue just the table. If its low you dont wear the cloth out from stroking and if its high then you protect the cue but risk denting the rail when in a hurry pounding feather strips in.
Smart installers no how to stay away from the rail and still set ther feather strips righ tnew ones or shimmed up to flush it up.
good point but everyone will have a different answer It's just a design error probably noone ever thought it out to the finish or spoke up when they thought it was wrong someone will think its right.
Just a can of worms with another 2cents thrown in..
Craig