This is true, but I've always taken it as a given that the particular degree stuff is just precision for precision's sake. I don't take it too seriously. I try to analyze what effective pros do and see how I can possibly train to hit in a similar way.
For example, if I find the racquet is too inline with my forearm at contact on the serve, I can move my toss more to the left and attempt to slightly drop the contact point.
Of course, for most rec-players, we need work on both technique and just basic stuff like moving our feet. Sometimes it is just helpful to be told you were standing around after you hit the ball in your match. You'd think that was just common sense, but on this board we actually have people arguing that split-stepping is for losers, etc. I think more of the criticism should be directed at those people rather than those obsessing on racquet angles in the optimal forehand.