The 7 inning double header rule exists in the minors as yet another way to coddle pitchers. MLB won't do it because it would remove 4 innings of baseball.
I'm still not biting on baseball this year.
This pandemic has pulled my interest in sports out from under me. My hope now is for normalcy in 2021, and that's not a certain thing.
With all the canceled games, double-headers will be required to make up most games.
MLB has "done it" - 7 inning games for double headers.
Aimed at saving pitchers a little.