Physics aside, you are correct to say that the technique for convex edges makes it easier for a beginner attain a sharp edge. Not only does it help minimize the bur, but you also do not have to be as concerned about angles (though maintaining about a 16-18ish angle and knowing to not using much pressure does help).
It certainly is easier just to "eye-ball" it this way. My main technique is to hold the edge as if I were "trying to shave the grit off the sandpaper," as one instruction source put it. No machines, no holders, no mathematics, just your eyes, and your fingers.