...makes one wonder. and to think there are certainly more than one grader signing off on the final grade determination. i guess that is certainly subjectivity!
The PCGS Grading Standards for MS70 state that the coin must be "As struck, with full strike". This means that there must not be any post-strike damage. As MDD occurs at the moment of strike, rather than after, it would not disqualify a coin from receiving a 70.
It actually says a whole lot more than that - but, it does make some exceptions which is what you are doing. Those exceptions are- toning - an coin can be toned and still be graded as MS70 "Minor die polish, light die breaks, and so on are not considered defects on business strike coins." Of course this presupposes that you as a collector believe in and follow the PCGS grading standards as they are written. But there is little reason to do so, because PCGS does not follow them to begin with.
Yes, I agree. There are solid 70's and borderline 70's (and certainly questionable 70's also), just like any grade. My point was that machine doubling by itself doesn't disqualify a coin from making the grade.