The message of a woman's greatest purpose in life is for reproduction is from men. The women who repeat this message are the ones who are conditioned to also think this way. It's a tool to manipulate women into becoming the "submissive housewife" so many men fantasize about.
Submissive housewife is just property in the eye of the husband. "My property, I do whatever I want with it", which also sounds eerily like slave ownership. It's dehumanizing and women might often not be aware of that.
To be fair, women with breasts, ovaries, and uteri are perfectly capable of being impregnated by a submissive pre-hrt trans girl. Perhaps cis women were created by Prometheus for the purpose of breeding submissive transbians
That's bullshit. One can brainwash women that their purpose is reproduction out of all kind of motivations. For example, some elderly will tell that lie to keep the young at bay while they don't necessarily believe it themselves. Another example, some religious people will say the same thing. Because they are stupid.