I don't think the mass loss due to wear is necessarily proportional to grading. A coin worn down on the rims will lose just as much mass as a coin worn down on the faces, but a worn-rim coin would be punished less in terms of grading. And obviously it's of no benefit in discerning between the MS grades.
Mass/weight is great for confirming:
- Authenticity: a coin that looks worn but isn't lightweight, or isn't worn but is considerably underweight, would both be questionable;
- The difference between worn/filled dies, weak strike, and actual wear.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis