I would disagree that a DH should not win MVP. We’ve all seen numerous no-field, all-bat first basemen win the award, and the token act of putting on a glove doesn’t make a player more valuable.
But in the case of Martinez, it’s hard to argue that his offensive contributions outweigh the offensive and defensive contributions of Betts, Trout, and Ramirez.
Were I a voting member of the BBWAA, Martinez would get a fourth place vote from me under the old system. Under the new “three nominee” system, he might not be nominated at all...