Yet, if you think about it, the lore regarding it comes down to a group of politically powerful windbags (high lords of terra) merely saying 'this shall not be' where, in the case of astartes, the lore states 'this cannot be'. Yet, from what I have seen, the astartes lore is consistently the one being questioned even though it is the most set in stone.
Long and short of short of it? It comes down to 2 reasons: 1. The Space marines get a lot more limelight. Hence all the interest around them. 2. Space Marines are (I think it is safe to say) just cooler than the Sisters. They get all the coolest toys, niftiest abilities, most badass back stories. Their most inexperienced and weakest members could take on dozens of regular humans. Their exploits are legend.
That's why, I think, a lot of people clamor for female Space Marines.
My post, if you read it carefully, is questioning why does this bit of lore need a reason above and beyond what is already stated?
Because we are curious beings and like to have things work in an internally consistent manner.
We don't just need to know that things work, we need to know why
Perhaps I am misunderstanding you here (or you are misunderstanding me). I am, in a round about sense, agreeing with the OP- astartes are only male.
Let me try to rephrase myself. Who in this thread has argued that there should
be female Space Marines? Like within the canon.
No one, to my knowledge.
I was just commenting that your little soapbox episode was very strange given the context of the rest of the thread.
You tried to tear apart an argument no one had made.