Edit : After a few discussions, I feel like making DM able to count for daily mission is good since these missions could already be done in 1 or 2 games in the first place so allowing DM to get them doesn't change anything, but DM restriction should still stay for weekly since DM would trivialize those missions and I don't want them to get any longer.

I really don't know why DM doesn't count toward mission in the first place, XP is already a pain in the ass to grind and DM should've never been restricted. Enabling mission on DM would really be a great quality of life and would reward player that goes HS only with that HS mission xp.