Let me throw my 2 cents in here before this break down into some stupid drama.
It's dumb. It's not the idea or the concept of female space marine. I like the some art out there of the idea. (
www.pixiv.net/en/artworks/110407676). It's the push for it is an agenda. Lot of the people pushing this are the type that have no personality outside of making political tweets all day. Space marines are the poster boys, so having female space marine would do nothing but the idea of some kind of victory.
Doesn't matter if there's female characters in the guard. Doesn't matter if there's female characters in the inquisition. Doesn't matter if there's female characters in the Mechanicum. The entire sisters of battle don't matter. Not of that matters as it's not in the main marketing push.