Bert, it is more of a respect thing than anything. But being a MST requires you to do annual training, so they would have to give you access to the portal for testing and training, which I think would include parts lookup, at least my MST account allows parts lookup.
I originally became an MST back in 2001 because my briggs field rep is a pain in the rear, and that is not the word I wanted to use, and thinks he is smarter than everybody else. Briggs tends to treat their MST's with more respect than just the normal techs.