The quote you provided is excellent. It doesn't justify spending big time money on a closer, but it does add some justification for having defined roles in the bullpen. Over the course of a 162 game season, it has to be grueling mentally and physically. Knowing what is expected of you day in and day out can really help with the mental preparation portion. To me this is a big reason the closer-by-committee has not taken as much of a front seat as numbers imply it should. Numbers struggle to capture the mental portion of the game.
Now that being said, I think pitching coaches could do a better job of utilizing pitchers in different situations. Not all the time but some of the time. For example:
1 or 2 run lead you are home team and it is bottom of the 6th. STL has the bottom 3 in the lineup due up. Why not get Chapman up and running right away that way he can have his time and get warmed up to likely face 1-2-3 or 2-3-4 in the 8th inning, he will have plenty of time to get loose and get through his routine. Or if the guy in the 7th really struggles, he may be able to come get out of a jam late in the 7th, if he is ready in time, he may not be depending on how quickly it occurs. I agree this situation could and should happen more than it does.
However, let Champan have a defined role of pitching the last 3 outs or so in save situations, but occasionally utilize him differently, with plenty of forewarning. Let the other guys maintain their usual roles, but occasionally use your big bullet differently.