Including women would have been a legal nonstarter.

The german constitution restricts drafting to men[0] and would have to be changed before such a law could even be considered.

Before you ask, yes, the constitution also says that men and women need to be treated equally[1]

[0] https://www.gesetze-im-internet.de/gg/art_12a.html

[1] https://www.gesetze-im-internet.de/gg/art_3.html

"gender is a social construct" only goes so far...