mouthpiece placement

A standing advice here on SOTW when people have problems with the soprano is "push the mpc as far as possible onto the cork". I have even gotten that advice from a mouthpiece maker. I have tried it, and it really works - except that the sax gets very sharp. So - why must the mouthpiece be so far...

While practicing Alto today, I decided to take in a lot of mouthpiece, to see if it would make a difference. I took in enough mouthpiece to cover up a majority of the Bite Plate with my front teeth, without it being uncomfortable. I do have a (very) slight overbite, but my lower lip still...